Little is known on long-term survival and causes of death among individuals born small or large for gestational age. This study investigates birth weight in relation to survival and causes of death over time.A national cohort of 1.7 million live-born singletons in Denmark was followed during 1979–2011, using the Danish Civil Registration System, the Medical Birth Registry and the Cause of Death Registry. Cox proportional hazards were estimated for the impact of small (SGA) and large (LGA) gestation weight and mortality overall, by age group and birth cohort.Compared to normal weight children, SGA children were associated with increased risk of dying over time. Though most of the deaths occurred during the first year of life, the cumulative mortality risk was increased until 30 years of age. The hazard ratios [HR] for dying among SGA children ages <2 years were: 3.47  and 1.06  in 30 years and older. HR for dying among SGA adults (20–29 years) were: 1.20  in years 1979–1982 and 1.61  in years 1989–1994. The SGA born had increased risk of dying from infection, heart disease, respiratory disease, digestive disease, congenital malformation, perinatal conditions, and accidents, suicide, and homicide. Individuals born LGA were associated with decreased mortality risk, but with increased risk of dying from malignant neoplasm.Survival has improved independently of birth weight the past 30 years. However, children born SGA remain at significantly increased risk of dying up till they turn 30 years of age. Individuals born LGA have lower mortality risk but only in the first two years of life. Several studies have investigated the association between birth weight and mortality and morbidity –4. How bOver the past 40 years perinatal care has improved survival of preterm and low-birth-weight infants tremendously. For example between 1995 and 2006, survival of preterm infants, born between 22 and 25 weeks’ gestation, improved by as much as 13% . SimilarIn the present study we took advantage of the unique population-based registries in Denmark to study the entire population of live-born children over a period of 30 years. We investigated how far into adulthood a child’s birth weight influences survival and studied the underlying cause of death.All children born in Denmark are assigned a civil personal registration number allowing for identity-secure linkage of information between national registries. We used data from the Civil Registration System (CRS)  to identth percentile birth weight among all infants within the same gestational week, with same gender and born within the same birth cohort were categorized as small for gestational age (SGA). Infants born above the 90th percentile birth weight among all infants within the same gestational week, with same gender and born within the same birth cohort were categorized as large for gestational age (LGA). Infants born within the 11–89% cut-off were categorized as ‘normal for gestational age’ and served as the reference group in most of the analyses.Unless otherwise specified, relative weight was defined as small, large and normal weight for gestational age. Infants born below the 10th Edition. The ten groups were; infection ; malignant neoplasm (ICD-10 code: C00-D09); heart disease ; respiratory disease (ICD-10 code: J00-J99); digestive disease (ICD-10 code: K00-K93); congenital malformation, deformations and chromosomal abnormalities (ICD-10 code: Q00-Q99); condition originating in the perinatal period (ICD-10 code: P00-P96); accident, suicide, and homicide (ICD-10 code: V01-Y89); other; and unknown.The relative weight categories were calculated within birth cohort year , gender and gestational age strata. Gestational age at birth was categorised as follows: 19–28 weeks, 29–31 weeks, 32–33 weeks, 34–35 weeks, 36 weeks, 37 weeks, 38–42 weeks, and 43–45 weeks, using mother’s information on first day of last menstruation and sonogram measurements. Only singletons with known gestational age between 19 and 45 gestational weeks and known birth weight between 500 and 7000 grams were included in the study. We compressed coding in the cause of death registry into ten groups using the International Classification of Diseases (ICD) 10Cox proportional hazards regression was used to estimate hazard ratios [HRs] and 95% confidence intervals [CIs] for the association between small and large gestation weight and mortality over time, using attained age  as the underlying time scale in all analyses. The baseline hazard function was stratified on gender and birth year. The assumption of proportional hazards was explored by use of cumulative residuals as described by Lin et al . In caseth, 10th, 20th, 40th, 60th and 80th percentile, with the 50th percentile as reference. Cause-specific probabilities of death were estimated non-parametrically with the Aalen-Johansen estimator [Individuals were considered at risk as long as they were registered as living in Denmark. Individuals who emigrated and later immigrated were censored at emigration and reincluded in the cohort at date of immigration to Denmark. To evaluate mortality by years of age, we defined age groups as follows: <2 years, 2–5 years, 6–13 years, 14–19 years, 20–29 years, and 30 years and older. The association between age and relative weight was estimated in each age group after excluding earlier deaths. We also considered the percentile of the relative birth weight as a continuous variable. The effect of this percentile was estimated with a cubic spline plot with knots specified at the 5All analyses were conducted using SAS 9.4 .The study was register-based and complied with the regulations and instructions set up by the Danish Data Protection Agency . We only used anonymized data, we only present data in aggregate and anonymous form, and we neither contacted any study participants nor required any active participation from them.Overall, 877 303 men and 831 411 women contributed at least one day of observation time between January 1, 1979, and December 31, 2011. Subjects were followed for 27 million person-years and 14 167 deaths occurred in the study period .The median birth weight changed over calendar time with individuals born between 1979 and 1982 having a median birth weight of 3410 grams and individuals born between 2007 and 2011 a median birth weight of 3550 grams . Though In the figures of cumulated residuals (not show) we observed violations of the proportional hazard assumption in the <2 years old, but no signs of model violations after the age of 2 years. Among SGA individuals, an up to 4.5 fold increased HR was found in the first days of life followed by a strong decline to a relative stable level of about 2.0–2.5 in the age span from 90 days to 2 years, th percentile were associated with increased risk of dying, compared with individuals born with normal weight. Conversely, individuals born within the higher percentiles, above the 50th percentile, were at modest decreased risk of dying, compared with individuals born with normal weight for gestation.In Among individuals born with extremely low birth weight, i.e. 500–1499 grams in weeks 19–28, the risk of dying dropped by more than 50% between 1979–1989 and 2000–2011,  Figs. AmAs given in When looking at mortality risk by birth cohort in strata of age groups and with one overall reference group , survivaThe cumulative mortality by any cause of death was estimated using the Aalen-Johansen estimator between years 1979 and 2011. Risk of death stratified by relative weight  and by disease group is shown in more detail, Individuals born SGA were at increased risk of dying, in all disease categories but malignant neoplasms, When we modelled the effect of relative weight as a function of age stratified by cause of death, SGA born individuals were at strongest increased risk of dying from infection; heart disease; respiratory disease; perinatal conditions; congenital malformation; accidents, suicide, and homicide during the first years of life. LGA-born individuals had a decreased risk of dying from congenital malformations and perinatal condition during the first years of life. Further, in the LGA-born individuals, the risk of dying from malignant neoplasms was highest between age 6 and 13 years, . Increased risk of dying from digestive disease , (2–5 years old) and heart disease , (14–19 years old) was also observed, Our study observed high mortality among individuals born small for gestational age between years 1979 and 2011. With a total of 1.7 million live-born children followed for 27 million person-years during a 30-year period, our study had unique power to describe the long-term survival among individuals born small and large for gestational age. This also allowed us to investigate how mortality decreased over calendar time independently of birth weight. In the USA reports have shown that prenatal and neonatal care improved during the 90’s [We are not aware of any other study that has reported on the association between being born small or large for gestational age and mortality risk up to 30 years after birth. Previous studies on this topic have primarily explored the association of birth weight and gestational age separately. As an example a study based on the Swedish medical birth registry reported increased mortality in infancy, early childhood and young adulthood among individuals born at 37–38 weeks of gestation . In the Mortality risks decreased over calendar time, but were still strong within each birth cohort among individuals born small for gestational age. Interestingly, though advanced neonatal care and improved survival of SGA individuals likely result in different long-term outcome for individuals born in the 1970’s and 2011, we observed similar increased risks in comparing SGA individuals to normal individuals with the highest difference in the later time period. A possible explanation to this could be that care of those born extremely early and/or extremely small have improved, consequently more extreme individuals survive their first day in life and are therefore more frequently included in the later cohorts. Thereby, one can argue that relative weight is a rough estimate, suggesting that the definition of SGA should be reconsidered.In general, SGA born individuals require more intervention, longer stay at hospital with neonatal care and are at risk for certain conditions compared to individuals born normal weight for gestational age. Preterm SGA and term SGA born individuals face different medical conditions. Previous report discovered that term born SGA individuals are likely related to sociodemographic status while preterm are related to chronic hypertension and preeclampsia . Also dith birth weight percentile, compared with the previously used 10th percentile [th percentile. We took into account birth cohort, gender and gestational age when setting the cut-offs for relative birth weight, and this difference in study design and study population could explain the dissimilarities comparing our results with earlier published results.In a previous study the authors observed a 2-fold increased risk of prenatal and neonatal death among term and post–term individuals in the 15rcentile . In our Some studies have reported an U-shaped association between birth weight and all-cause mortality . OverallThe major strengths of the present study are the prospective study design, the long follow-up, and the large sample size. The registry-based design allowed us to assemble a nationwide cohort with independent ascertainment of exposure and outcome and complete follow-up of all infants with accurate longitudinal information. In Denmark health care is free of charge and encouraged for all pregnant women irrespective of income and immigrant status. We used the Danish CRS ;19 and tIn conclusion, our findings suggest that weight by gestational age at birth is an important predictor for mortality from birth until approximately at least 30 years of age. Multiple causes of death were associated with being born small for gestational age during this age span.S1 Aggregated Data(ZIP)Click here for additional data file.S1 Fig(PDF)Click here for additional data file.S2 Fig(PDF)Click here for additional data file.S3 Fig(PDF)Click here for additional data file.S4 Fig(PDF)Click here for additional data file.S5 Fig(PDF)Click here for additional data file.S1 Table(DOC)Click here for additional data file.


Overweight and obesity during pregnancy represents a considerable health burden. While research has focused on interventions to limit gestational weight gain, there is little information describing their impact on neonatal health. Our aim was to investigate the effect on a range of pre-specified secondary neonatal outcomes of providing antenatal dietary and lifestyle advice to women who are overweight or obese.2 or over, and singleton gestation between 10+0 and 20+0 weeks. Outcome measures included gestational age at birth; Apgar score below 7 at 5 minutes of age; need for resuscitation at birth; birth weight above 4.5 kg or below 2.5 kg; birth weight, length and head circumference (and Z-scores); admission to the nursery; respiratory distress syndrome; and postnatal length of stay. Data relating to the primary outcome  and birth weight above 4 kg have been reported previously. Analyses used intention-to-treat principles.We report a range of pre-specified secondary neonatal outcomes from a large randomised trial in which antenatal dietary and lifestyle advice was provided to women who were overweight or obese. Pregnant women were eligible for participation with a body mass index of 25 kg/mP = 0.04), or respiratory distress syndrome , particularly moderate or severe disease, and had a shorter length of postnatal hospital stay  compared with infants born to women who received Standard Care.In total, 2,142 infants were included in the analyses. Infants born to women following lifestyle advice were significantly less likely to have birth weight above 4.5 kg  = 0.59; 95% confidence interval (CI) 0.36 to 0.98; For women who are overweight or obese, antenatal dietary and lifestyle advice has health benefits for infants, without an increase in the risk of harm. Continued follow-up into childhood will be important to assess the longer-term effects of a reduction in high infant birth weight on risk of child obesity.http://www.biomedcentral.com/1741-7015/12/161 and http://www.biomedcentral.com/1741-7015/12/201.Please see related articles: ACTRN12607000161426)Australian and New Zealand Clinical Trials Registry ( Globally, it is estimated that 170 million children under the age of 18 years , and 21%The economic costs of childhood obesity are profound . AustralThe intra-uterine environment is recognised as playing a key role in the development of later health and disease , represeAlthough there is considerable research focused on the effects of dietary and lifestyle interventions to limit gestational weight gain by pregnant women who are overweight or obese, their effect on neonatal outcomes has been poorly reported in the literature to date -22. In tEthics approval was granted by the Women’s and Children’s Local Health Network Human Research and Ethics Committee at the Women’s and Children’s Hospital, the Central Northern Adelaide Health Service Ethics of Human Research Committee  and the Flinders Clinical Research Ethics Committee . Approval to conduct the trial was provided by the Human Research and Ethics Committee at each participating centre, and all participants provided written informed consent.We conducted a multicentre randomised trial across the three major metropolitan maternity hospitals within Adelaide, South Australia. The methods  and prim2 or greater and singleton pregnancy between 10+0 and 20+0 weeks gestation were eligible to participate in the trial. Women with a multiple pregnancy, or type 1 or 2 diabetes diagnosed prior to pregnancy were ineligible.Women with a BMI of 25 kg/mAll women had their height and weight measured and their BMI calculated at their first antenatal appointment, and eligible women were counselled about participation.2 versus ≥30 kg/m2), and collaborating centre. Women were randomised and allocated to either ‘Lifestyle Advice’ or ‘Standard Care’.Randomisation occurred by telephoning the central randomisation service, using a computer-generated schedule, with balanced variable blocks, and stratification for parity (0 versus ≥1), BMI at antenatal booking  >0.80 with ventilation); proven systemic infection requiring treatment; retinopathy of prematurity; necrotising enterocolitis; neonatal encephalopathy [In clinical practice, there is considerable variation in definitions of ‘large for gestational age’, including birth weight at or above the 90th centile for gestational age and infant sex, birth weight above 4 kg, and birth weight above 4.5 kg, which are often used interchangeably. These have been recognised as associated with early childhood obesity ,27, and alopathy ; seizure3). Predicted fat free mass was calculated using the following formula:Ponderal Index was calculated using birth weight and length , or Fisher’s exact test with no imputation for rare outcomes. Continuous outcomes were analysed using linear regression, with treatment effects expressed as differences in means. Count outcomes were analysed using Poisson regression, or using negative binomial regression where over-dispersion was present, with treatment effects expressed as ratios of means.P < 0.05 (two-sided) with no adjustment for multiple comparisons. All analyses followed a pre-specified statistical analysis plan and were performed using SAS software .Both unadjusted and adjusted analyses were performed, with adjustment for the stratification variables. Outcomes derived from birth weight were additionally adjusted for maternal age, socioeconomic status and maternal smoking. Statistical significance was considered at Our predetermined sample size of 2,180 women was based on our primary trial outcome, the incidence of large for gestational age infants .Between June 2008 and December 2011, we recruited and randomised 2,212 women, with 1,108 allocated to receive Lifestyle Advice, and 1,104 Standard Care  (Table P = 0.04), compared with infants born to women allocated to Standard Care. This finding is consistent with our previous report of a significant 18% RR reduction in birth weight above 4 kg [P = 0,04) than infants born to women allocated to Standard Care.There were no statistically significant differences identified between the two treatment groups with regards to gestational age at birth  0.10 to 0.23; ove 4 kg . FurtherP = 0.06). However, infants born to women following Lifestyle Advice were less likely to have respiratory distress syndrome , particularly moderate or severe respiratory disease , compared with infants born to women allocated to Standard Care (Table P = 0.006). There were no other statistically significant differences in infant outcomes identified between the groups.There was no statistically significant difference in infant admission to neonatal intensive care .Our findings indicate that provision of lifestyle advice to women who are overweight or obese during pregnancy is associated with a significant reduction in the risk of birth weight above 4.5 kg, in addition to a significant reduction in risk of respiratory distress syndrome, particularly moderate or severe disease, and a shorter postnatal hospital length of stay. Importantly, we did not identify any increase in the risk of harm, including low infant birth weight.Our randomised trial has a number of strengths, including being the largest to date to evaluate the effect on clinically relevant neonatal outcomes of an antenatal lifestyle intervention for overweight or obese women. We utilised robust methodology, including blinding of outcome assessors and central randomisation, and achieved a high rate of infant follow-up and available birth outcome data.Our trial is not without limitations. As highlighted previously , a potenThe findings of a significant 41% RR reduction in birth weight above 4.5 kg among infants born to women following Lifestyle Advice compared with Standard Care is consistent with the 18% RR reduction in birth weight above 4.0 kg reported previously . ImmediaWe observed a 53% RR reduction in neonatal respiratory distress syndrome in infants born to women allocated the lifestyle intervention. This difference in neonatal respiratory distress syndrome was not explained by differences in the use of antenatal corticosteroids, or in differences in gestational age at birth. Some of this difference may reflect the observed 26% reduction in preterm birth and the 53% reduction in preterm pre-labour ruptured membranes (PPROM) among women in the intervention group , althougIncreasingly, there is recognition that although the consequences of preterm birth and prematurity can occur in a setting of clinical chorioamnionitis, effects are also evident following subclinical or histological inflammation . HoweverTo our knowledge, our findings are the first to describe a significant reduction in neonatal respiratory morbidity among infants born to women who are overweight or obese following an antenatal dietary and lifestyle intervention. Furthermore, we postulate that this may be mediated by the significant improvements in maternal diet and physical activity following antenatal intervention, which we have reported previously . It willEvidence to date about the effect of antenatal dietary and lifestyle interventions for women who are overweight or obese has focused on gestational weight gain, to the detriment of robust data describing both maternal and infant health outcomes . Our ran


We investigated whether changes in perinatal outcomes occurred following introduction of key tobacco control policies in the Netherlands: smoke-free legislation in workplaces plus a tobacco tax increase and mass media campaign (January-February 2004); and extension of the smoke-free law to the hospitality industry, accompanied by another tax increase and mass media campaign (July 2008). This was a national quasi-experimental study using Netherlands Perinatal Registry data . Primary outcome measures were: perinatal mortality, preterm birth, and being small-for-gestational age (SGA). The association with timing of the tobacco control policies was investigated using interrupted time series logistic regression analyses with adjustment for confounders. Among 2,069,695 singleton births, there were 13,027 (0.6%) perinatal deaths, 116,043 (5.6%) preterm live-births and 187,966 (9.1%) SGA live-births. The 2004 policies were not associated with significant changes in the odds of developing any of the primary outcomes. After the 2008 policy change, a -4.4%  decrease in odds of being SGA was observed. A reduction in SGA births, but not preterm birth or perinatal mortality, was observed in the Netherlands after extension of the smoke-free workplace law to bars and restaurants in conjunction with a tax increase and mass media campaign. Tobacco use is associated with six million deaths annually making it the leading global cause of preventable deathCompelling evidence supports a causal role of SHS exposure in the development of numerous health hazards in adults5Through reducing maternal smoking and SHS exposure, tobacco control policies have considerable potential to benefit perinatal health. Tobacco tax increases have been associated with dose-dependent reductions in key adverse perinatal and infant outcomes7891213141511131315st, 2004, and was accompanied by a tobacco tax increase and mass media campaign. On July 1st, 2008 the smoke-free law was extended to the hospitality industry , and at the same time another tobacco tax increase and mass media campaign were introduced. In this study we investigated whether these joint introductions of tobacco control policies in the Netherlands were associated with changes in key perinatal outcomes known to be associated with maternal smoking and/or SHS exposure.In the Netherlands there have been two key moments at which tobacco control policies have been jointly implemented. A smoke-free workplace law was introduced on January 1We undertook a national quasi-experimental study, which involved analysing the association between the 2004 and 2008 joint introduction of tobacco control policies and perinatal mortality, preterm birth, and SGA births using monthly data from a comprehensive dataset of singleton births in the Netherlands between 2000 and 2011. We pre-specified all analyses in a registered study protocol: ClinicalTrials.gov NCT02189265.Based on existing literature we have developed a conceptual framework underpinning this work, outlining the various ways in which tobacco control policies are likely to affect pregnancy outcomes . Our datIndividual-level health care data were obtained from the Netherlands Perinatal Registry (PRN) between 2000 and 2011, inclusive. The PRN database is a validated linkage of three different national registries: a midwifery registry (LVR1), an obstetrics registry (LVR2) and a neonatal registry (LNR)+0 to 42+6 weeks of gestation. Pregnancy dating was performed by last menstrual period and/or first trimester crown-rump length measurement using ultrasound. While the latter is known to have been used increasingly over the study periodThe study population comprised all registered singleton births (i.e. stillbirths and live-births) occurring between 2000 and 2011 between 24In 1990, the first smoke-free law was introduced in the Netherlandsst, 2004 an amendment was introduced prohibiting smoking in workplaces and public transport, accompanied by a mass media campaign. Exceptions to this smoking ban were: hotels, bars and restaurants, sports, arts and culture venues, amusement arcades, tobacconist shops, international passenger transport, private spaces, open air, and designated areas for smoking within each facilityOn January 1st, 2008, the smoke-free legislation was extended to include hospitality venues, making it illegal to smoke inside hotels, bars and restaurants, sports, art and culture venues, amusement arcades, tobacconist shops, and international passenger transportOn July 1rd, 2010 an exemption to the July 2008 smoking ban was made for bars with a surface area of 70 square meters or less, and with no other personnel than the ownerOn November 3+0 weeks of gestation), and being born SGA (live-birth with birth weight below the 10th centile). Secondary outcome measures were: stillbirth, early neonatal mortality, very preterm birth (live-birth before 32+0 weeks of gestation), low birth weight , very low birth weight , very SGA (live-birth with birth weight below 2.3rd centile), and congenital anomalies. Congenital anomalies associated with antenatal smoke exposure were selected based on a systematic review on the association between maternal smoking in pregnancy and birth defectsOur main outcome measures were: perinatal mortality  combined), preterm birth We obtained the following demographic, obstetric, and neonatal characteristics: maternal age , ethnicity Monthly incidences for each outcome were calculated to facilitate visualisation of temporal fluctuations and trends in changes of incidence levels. Interrupted time series logistic regression analyses with adjustment for potential confounders were performed to assess the associations between the 2004 and 2008 implementation of tobacco control policies and the odds of developing each of the primary and secondary outcome measures. The models accounted for the underlying temporal trend in odds of developing each outcome, and allowed for a sudden change (‘step change’) following the introduction of the policies over and above the underlying trend. Using Akaike’s and Schwarz’s Bayesian information criteria  we selected the optimal model among three options that varied in their modeling of the underlying temporal trend, which was modelled via linear, quadratic, and cubic B-splines, respectively, to capture possible non-linearity in the underlying time trends. A continuous time variable based on month of birth was used. By using a dummy variable for each combination of tobacco control policies (coded ‘0’ before and ‘1’ after introduction of the policies), the step changes for the odds of developing each outcome were modeled. A backward selection procedure was not applied and both intervention dummy variables were thus retained in each model. Babies were assigned to the period before or after the ban based on birth month. To account for seasonality, a categorical variable for month of birth was added.The following categorical variables were included in the model to adjust for potential confounding at the individual level: maternal age, parity, urbanisation level, ethnicity, SES, pre-eclampsia, mode of delivery, and sex of the newborn. For the outcomes of stillbirth and perinatal mortality, mode of delivery was not included in the model. The primary analyses were performed using complete cases only  and their respective 95% confidence intervals (CIs) for the post-policy period versus the pre-policy period as % change in the post- as compared to the pre-policy period, using the following conversion:For the primary outcome measures, we performed three sets of pre-specified sensitivity analyses to test the robustness of our results.In the first set, we only included cases for whom pregnancy dating in the registry was recorded as ‘certain’ (93% of records). For the primary outcomes preterm birth and SGA, the model was thus re-run following the exclusion of cases in which gestational age was coded ‘not certain’. As this item had only been recorded from 2002 onwards, these analyses were restricted to the time period 2002–2011.+0 weeks of gestation were excluded. Perinatal management in the Netherlands changed in 2010 with an increased active management for newborns born at the edge of viability (i.e. 24–25 weeks of gestation)In the second set, cases with preterm birth before 26In the third set, we stratified preterm births into spontaneous preterm births versus medically indicated (i.e. induced) preterm births to account for a potential change in clinical practice over time. Furthermore, using this analysis we could assess whether there was a differential association between the introduction of tobacco control policies and the type of preterm birth.To test whether the findings were sensitive to missing data on individual-level covariates, multiple imputations using chained equations were performed, creating five unique datasets. We imputed the following variables: maternal age, ethnicity, SES, urbanisation level, parity, pre-eclampsia, mode of delivery, and sex of the newborn. Imputation was informed by both the outcome and the following predictor variables: gestational age and birth weighta priori planned to perform subgroup analyses according to maternal smoking status during pregnancy. However, maternal smoking during pregnancy was only recorded in <1% of the study population, which, based on prior studies, was considered to be a highly implausible smoking rate, indicating likely under-recordingWe To estimate the impact of the tobacco control policies in terms of the number of outcome events averted, counterfactual scenarios were developed for those outcomes for which a statistically significant association was observed. In these counterfactual scenarios, the odds of developing each outcome were estimated for the hypothetical situation of no policies having been introduced. The betas of each variable in the primary logistic regression models were used to calculate predicted values of the number of events, while setting the dummy variable of the policy of interest to ‘0’ for the entire study period. The estimated number of cases averted was then calculated by subtracting the actual number of events from the predicted number of events calculated based on the counterfactual model for each time interval.All analyses were performed on a password-secured stand-alone computer located at PRN using Stata SE 12.0  and SAS version 9.3 . The Stata analysis code is provided as an online supplement.The executive board of the PRN registry reviewed the protocol and gave their approval for the use of PRN data for this study . PRN data are anonymised; therefore according to Dutch law, formal ethical assessment of the study protocol was not needed.st, 2000 and December 31st, 2011, 2,191,047 births were registered. We excluded newborns born at <24 weeks of gestation or with unknown gestational age , multiple pregnancies , newborns with a birth weight <500 grams  and newborns with chromosomal anomalies .


To test the contraceptive confidence hypothesis in a modern context. The hypothesis is that women using effective or modern contraceptive methods have increased contraceptive confidence and hence a shorter interval between marriage and first birth than users of ineffective or traditional methods. We extend the hypothesis to incorporate the role of abortion, arguing that it acts as a substitute for contraception in the study context.Moldova, a country in South-East Europe. Moldova exhibits high use of traditional contraceptive methods and abortion compared with other European countries.Data are from a secondary analysis of the 2005 Moldovan Demographic and Health Survey, a nationally representative sample survey. 5377 unmarried women were selected.The outcome measure was the interval between marriage and first birth. This was modelled using a piecewise-constant hazard regression, with abortion and contraceptive method types as primary variables along with relevant sociodemographic controls.Women with high contraceptive confidence (modern method users) have a higher cumulative hazard of first birth 36 months following marriage (0.88 (0.87 to 0.89)) compared with women with low contraceptive confidence ). This is consistent with the contraceptive confidence hypothesis. There is a higher cumulative hazard of first birth among women with low (0.80 (0.79 to 0.80)) and moderate abortion propensities (0.76 (0.75 to 0.77)) than women with no abortion propensity (0.73 (0.72 to 0.74)) 24 months after marriage.Effective contraceptive use tends to increase contraceptive confidence and is associated with a shorter interval between marriage and first birth. Increased use of abortion also tends to increase contraceptive confidence and shorten birth duration, although this effect is non-linear—women with a very high use of abortion tend to have lengthy intervals between marriage and first birth. The study uses a nationally representative survey.Use of regression analysis disentangles the net effects of related contraceptive and abortion behaviour.Use of retrospective data necessitates reliance on proxy measures.–Over the past two decades, many countries in Eastern Europe have experienced an unprecedented decline in fertility with a total fertility rate at or below 1.3 children/woman.4–15The dynamics of contraceptive use including discontinuation rates, switching and method efficacy is widely acknowledged in demographic research.7While previous studies have addressed second and later birth intervals, the demographic landscape of Europe has undergone unprecedented changes in recent decades driven mostly by changes in the relationship between partnership formation—particularly marriage—and childbearing.We note that the pattern of union formation is an exceptionally complex demographic process.–In Moldova, traditional methods are still widely used: about 26% of the contraceptive methods used in Moldova are traditional.22The analysis considers marriage cohorts to capture changes in first birth rate as well as to ascertain the possible effects of exogenous economic uncertainty and poverty in delaying first birth. Other analyses17Data for this study are drawn from the birth history schedule of the 2005 MDHS. Details of the MDHS, including the sample design and questionnaire, are available elsewhere.23From the original MDHS sample of 7440 women, 1884 women were excluded since they were never married and 74% of these reported having never had sex. In addition, 179 women who had premarital births (2.4%) were excluded since the terminal event (first birth) preceded the start event (marriage). The final selected sample considers 5377 married women. About 15% of births occurred within 9 months of marriage—indicative of premarital conception. The MDHS also includes detailed information of abortion histories including the number and timing of each abortion.The analysis uses a piecewise-constant hazard model. The dependent variable is the timing of first birth  since first marriage (start event), recorded in months and expressed asIn A piecewise-constant hazard model uses a simplified data structure compared with a standard discrete-time model, as the duration variable is collapsed into intervals, across which the hazard of a birth is assumed to be constant. The advantage of this is that the baseline hazard distribution The main interest in the analysis of the first birth interval is the degree of contraceptive confidence. As noted by Ní Bhrolcháin,This analysis defines low contraceptive confidence for women who reported using a traditional method , moderate contraceptive confidence for those using a modern reversible method  and high contraceptive confidence for women using a permanent method (5%), either female or male. About 37% of women in the analysis sample have reported not using any method: contraceptive confidence for these women cannot be observed. We retain these women in the analysis, however, since their abortion history is still important in a context where abortion is normative fertility control behaviour. We include two controls relevant to contraceptive behaviour: the month and year of first method use and another variable measuring the previous method discontinued.To capture the latent effect of abortion propensity, the analysis uses abortion history as a proxy measure. Unfortunately, the MDHS has not collected any data on abortion attitudes. We therefore use the proportion of pregnancies a woman has terminated. A simple count is inadequate since older women have greater exposure to multiple abortions, which may introduce bias. Using the proportion of pregnancies aborted overcomes this problem. Other than recall problems inherent in cross-sectional surveys, any deliberate under-reporting of abortion in postsocialist countries is very low.Another key predictor variable is the marriage cohort, which is intended to capture the changes in first birth rate, which is often determined by economic circumstances, especially the availability of housing.The regression results adjusting for relevant confounders and control variables are presented for three selected effects: (1) marriage cohorts, (2) contraceptive confidence and (3) abortion propensity. The final model is presented in online supplementary table A1. Owing to the interaction terms and time dependency specified in the model, it is difficult to interpret coefficients directly, in particular the assessment of statistical significance of overall probabilities. We therefore use this model to generate estimated survival curves and cumulative hazards, and report the cumulative hazard of first birth at 12, 24 and 36 months after marriage as a summary statistic in The adjusted hazard rate of a first birth for each duration since marriage is estimated for different marriage cohorts. The results are shown in the form of survival plots , truncatWomen married during 1970–1979, 1980–1984 and 1985–1989 exhibited homogeneous survival trajectories, indicating rapid transition to motherhood: more specifically, 70% of women have had their first child within the first 2 years of their marriage. However, there is a distinct slowing trend in the transition to first birth within the first 24 months following marriage among those married during and after the post-independence period (1990–1994 birth cohort onwards). This trend is roughly linear as depicted in the survival curves shifting upwards, suggesting an increasing delay in first birth. The curve for the 1995–2000 cohort overlaps with the most recent cohort after 24 months, which suggests a propensity for early transition to motherhood among recently married women. That said, the overall probability of having a birth remains relatively constant—for instance 3 years following marriage the 1990–94, 1995–99 and 2000 or more recent cohorts have the same cumulative hazard of birth as the presocialist  marriage cohorts. This is largely due to the recuperation effect 2–3 years following marriage, suggesting that although the interval between marriage and first birth is longer, the probability of giving a birth does not vary across cohorts.This is also reflected in the cumulative hazard, with the hazard among the preindependence cohorts at 41%, 75% and 86% for 12, 24 and 36 months, respectively. However, there is a considerable fall in the cumulative hazard for the 1995–1999 and 2000 marriage cohorts, indicating the increasing delay of first birth following the collapse of Socialism, but overall Moldovan women have a consistently high probability of becoming mothers.The estimated survival curve for each level of contraceptive confidence is presented in Among women with a measurable contraceptive level , the survival curve for high contraceptive confidence is the highest, indicating the slowest transition to first birth in this group. The first birth rate is higher for women with moderate contraceptive confidence, compared with women with low contraceptive confidence. The survival curve for high contraceptive confidence is comparable to those of the low confidence group until 24 months following marriage , when there is a rapid fall in the proportion of women yet to have first births. This indicates that, in general, low contraceptive confidence is associated with low hazard of first birth and hence longer duration between marriage and first birth. On the other hand, an increase in contraceptive confidence is associated with increased hazard of first birth, which clearly suggests rapid transition to motherhood among women with high confidence.The estimated survival curve of first birth for women with low contraceptive confidence is presented in This study examined the impact of contraceptive confidence on the shifts in timing of first birth in a low fertility regime with high abortion rates. The analysis yielded three key findings. First, there is evidence of contraceptive confidence effect on the timing of first birth: women with low contraceptive confidence tend to delay their first birth, while women with high contraceptive confidence progress more rapidly to motherhood. The results supported the hypothesis that women using effective methods have increased contraceptive confidence and a relatively shorter interval between marriage and first birth than users of ineffective methods. This result has wide-ranging implications in the low fertility context of Moldova where modern methods are not widely available and many women rely on traditional methods for fertility control. Second, overall use of abortion results in a shorter interval between marriage and first birth, particularly for women with low contraceptive confidence. We do note, however, that this effect is non-linear: an increasing propensity to use abortion  will tend to depress overall fertility behaviour. Abortion appears to be an effective substitute for women with low contraceptive confidence, suggesting that voluntary abortion tends to potentially outweigh traditional method failure. An efficient strategy to reduce increasing abortion rates, therefore, is to increase access to modern methods to young couples in Moldova. Third, the study provides evidence of increase in the duration between marriage and first birth for recent marriage cohorts, although motherhood is still common among Moldovan women. This development is consistent with the increasing trend in fertility postponement behaviour as well as increasingly complex co-relationships between fertility and marriage in the Moldovan setting,27


In most high and middle income countries across the world, at least 1:4 women give birth by cesarean section. Rates of labour induction and augmentation are rising steeply; and in some countries up to 50 % of laboring women and newborns are given antibiotics. Governments and international agencies are increasingly concerned about the clinical, economic and psychosocial effects of these interventions.There is emerging evidence that certain intrapartum and early neonatal interventions might affect the neonatal immune response in the longer term, and perhaps trans-generationally. Two theories lead the debate in this area. Those aligned with the hygiene (or ‘Old Friends’) hypothesis have examined the effect of gut microbiome colonization secondary to mode of birth and intrapartum/neonatal pharmacological interventions on immune response and epigenetic phenomena. Those working with the EPIIC (Epigenetic Impact of Childbirth) hypothesis are concerned with the effects of eustress and dys-stress on the epigenome, secondary to mode of birth and labour interventions.This paper examines the current and emerging findings relating to childbirth and atopic/autoimmune disease from the perspective of both theories, and proposes an alliance of research effort. This is likely to accelerate the discovery of important findings arising from both approaches, and to maximize the timely understanding of the longer-term consequences of childbirth practices. For most of human history birth has been seen as a social event occurring at home amongst family and friends with minimal intervention , 2. HoweMore recently, concern has been expressed that the pendulum has swung excessively towards prophylactic and unnecessary interventions for childbearing women and babies - ‘just in case’ . In mostMore recently some researchers have begun to examine the rapid rise in intrapartum interventions such as caesarean sections , 15, theTwo theories lead the debate in this area. Those aligned with the hygiene (or ‘Old Friends’) hypothesis have examined the effect of gut microbiome colonization secondary to mode of birth and intrapartum/neonatal pharmacological interventions on immune response and epigenetic phenomenon , 21. ThoEach body cell has the same DNA and genes, but their expression can vary . EpigeneDNA methylation is a specific epigenetic alteration in which a methyl group attaches to a cytosine (C) residue in DNA, which is followed by a guanine (G) residue connected by a phosphate bond, commonly referred to as a CpG dinucleotide. Between 60 and 90 % of cytosines are methylated in human DNA  and the DNA methylation patterns are known modulators of immune function and alterations have been associated with processes that moderate immune development. Examples of these are listed in Table Supporters of the ‘hygiene hypothesis’ have proposed that over the past century declining family size, improved household amenities, and higher standards of personal cleanliness have reduced opportunities for cross infection in young families leading to more widespread expression of allergy responses. Strachan  was one These, and similar critiques, have led to what has been termed the ‘extended hygiene hypothesis’ suggesting that, rather than waiting for exposure to bacteria to prime the immune system, in-utero, and in the first hours, weeks or months of life, the baby needs to gather a community of pre-existing microbes that come from the mother, as well as from the surrounding environment. Establishing the gut microbiota (which is increasingly being described as an active organism rather than a passive colonisation) may be important in protecting the child and later on the adult against atopic and immunological diseases . DisturbThe extended hygiene hypothesis may be supported by evidence that babies born by caesarean delivery have different gut microbiota in the first hours and days of life to those born vaginally, suggesting that the route of birth may be fundamental to the physiology of the gut flora. The recent CHILD study from Canada used DNA sequencing to detect microbes in faecal samples from infants at age four months. They found infants born by caesarean delivery have low bacterial richness and diversity compared to those born vaginally . There iThere is also evidence to indicate a marked increase in children’s susceptibility to a range of immune related disorders if they are born by caesarean delivery, and particularly when it is performed electively without concurrent labour . FollowiCXCL16) gene occurred when specific pathogens were not present during early life development. The CXCL16 gene encodes a chemokine receptor on invariant natural killer T cells (iNKT), resulting in higher accumulations of iNKT cells that are involved with inflammatory processes. Thus higher accumulation of the iNKTs only occurred in the colon and lung when specific bacteria were not present. The authors hypothesized an environmental exposure later in life triggers various inflammatory disease processes programmed by the altered methylation in the bowel and lungs, such as asthma and irritable bowel syndrome. Therefore, exposure to bacteria early in development affects the programming of the immune system, in mice, by causing perturbation in DNA methylation patterns. They concluded the findings could be extrapolated to humans because the mouse model used is similar to human cells. Further studies investigating alterations of methylation patterns in humans related to the effects of antibiotics and subsequent alteration in the microbiome could identify mechanisms of altered immune programming, and this may begin at the point of entry at birth. These findings have relevance to early infant development and mode of feeding.Alterations in DNA methylation patterns related to altered initial colonization of the gut have been identified in animal models. Back in 1915, Kendall determined that microbes, which colonize the gastrointestinal tract at birth, were involved in normal development of the immune system . HoweverMode of birth  and whether or not the infant breastfeeds are also being studied as possible determinants of gut microbiota development , 52. CaeTo date, primary research outcomes for studies investigating intrapartum antibiotic administration have been related to maternal illness and health outcomes . IntrapaThe EPIIC hypothesis published in 2013 proposes that, when labor and birth occurs primarily without intervention  a healthy positive form of stress (eustress) is exerted on the fetus . This thp = 0.02). There was also a strong CpG-specific relationship between the duration of labour and locus specific DNA methlyation in a subset of identified genes. The authors hypothesize that altered methylation can create poised, replication-heritable epigenetic marks, not immediately influencing gene transcription until a second hit arrived causing disease. The authors concluded that mode of delivery affects the epigenetic state of neonatal hematopoietic stem cells and this may have implications for health and disease in later life. Interestingly the authors make the point that while the hygiene hypothesis postulates that it is the lack of colonization of the infant with maternal gut flora after caesarean that may prevent the initiation of the immune system of the newborn, they found a correlation between the duration of labour and DNA methylation, indicating that methylation status at the start of vaginal birth resembles that of caesarean born infants (unexposed to labour and ruptured membranes), after which DNA methylation differences progressively change along with delivery. They suggest this shows the findings are directly related to labour itself [Others have shown differences in DNA methylation at the time of birth, by mode of birth , 67. VerUse of intrapartum oxytocin is increasing, and this is important in terms of the influence of oxytocin on stress response and maternal-paternal-infant bonding in the first few days of life . AlteredGiven the known link between the stress response, subsequent DNA methylation patterns and epigenetic changes that are associated with auto-immune response,  the EPIIGiven that environmental exposures may alter DNA methylation patterns associated with phenotypic differences in adults, it is likely that preconception and antenatal exposures could influence the epigenetic signature of the developing fetus. The timing, duration, combination, and pattern of exposures play a critical role in contributing to the development of altered phenotypes . In thisTogether or separately, the mounting evidence related to both the extended hygiene hypothesis (EHH) and the EPIIC hypothesis suggests that factors occurring during the intrapartum and early postnatal period may lead to fetal epigenomic remodeling anomalies, which exert influence on abnormal gene expression. These include mode of birth, dys-stress during labour and in the early postnatal period , and/or the effect of pharmacological agents such as antibiotics, or of mode of infant feeding Fig. .Fig. 1AdIt is highly likely than more than one factor is behind the recent rise in atopic and autoimmune disease, and a combination of the extended hygiene hypothesis and EPIIC hypothesis may provide interesting answers in the future. In this paper we have further developed on the EPIIC hypothesis, which was published in 2013, to encourage researcher to consider the complexity and interconnectivity of this hypothesis with others such as the EHH. We propose an alliance of research effort. In the first instance, information is required about the baseline physiology of labour and birth. It is very unlikely that this can be done in hospital maternity wards, where most births take place, as the protocols and procedures and routine interventions used in maternity care in most hospitals across the world militate against physiological processes of birth. It is therefore vital to carefully examine the normal physiology of labour and birth in settings where women are undisturbed as far as possible. This is likely to be in birth centres, and at home births. Once this baseline is established, interventions in the process, such as caesarean section, use of forceps, induction of labour, augmentation with oxytocin and the introduction of antibiotics, should also be explored for their short- and long-term effects. Collaboration of scientists in these efforts is likely to accelerate the discovery of important findings arising from both approaches, and to maximize the timely understanding of the longer-term consequences of the way childbirth is currently managed in most countries of the world.Although this paper focuses on a specific hypothesis relating to epigenetic changes during childbirth and the possible consequent effects on immunity, we are aware that other mechanisms and health outcomes could be involved . For exaIn this paper we examine the current and emerging findings relating to childbirth and atopic/autoimmune disease from the perspective of both the Extended Hygiene Hypothesis (EHH) and the Epigentic Impact of Childbirth (EPIIC) hypothesis and we propose an alliance of research effort. This is likely to accelerate the discovery of important findings arising from both approaches, and to maximize the timely understanding of the longer-term consequences of childbirth practices.


Previous studies indicated an association between intrauterine exposure to perfluorooctane sulfonate (PFOS) or perfluorooctanoate (PFOA) and lower birth weight. However, these perfluoroalkyl acids (PFAAs) have to some extent been substituted by other compounds on which little is known.We investigated the association between specific PFAAs and birth weight, birth length, and head circumference at birth.We studied 1,507 mothers and their children from the Aarhus Birth Cohort (2008–2013). Nulliparous women were included during pregnancy, and serum levels of 16 PFAAs were measured between 9 and 20 completed gestational weeks (96% within 13 weeks). For compounds with quantifiable values in > 50% of samples (7 compounds), we report the associations with birth weight, birth length, and head circumference at birth determined by multivariable linear regression.Estimated mean birth weights were lower among women with serum perfluorohexane sulfonate, perfluoroheptane sulfonate, and PFOS concentrations above the lowest exposure quartile, but we found no consistent monotonic dose–response patterns. These associations were stronger when the population was restricted to term births . For PFOS, the birth weight estimates for the highest versus lowest quartile were –50 g  in all births and –62 g  in term births. For the other PFAAs, the direction of the associations was inconsistent, and no overall association with birth weight was apparent. No PFAAs were associated with birth length or head circumference at birth.Overall, we did not find strong or consistent associations between PFAAs and birth weight or other indices of fetal growth, though estimated mean birth weights were lower among those with exposures above the lowest quartile for some compounds.Bach CC, Bech BH, Nohr EA, Olsen J, Matthiesen NB, Bonefeld-Jørgensen EC, Bossi R, Henriksen TB. 2016. Perfluoroalkyl acids in maternal serum and indices of fetal growth: the Aarhus Birth Cohort. Environ Health Perspect 124:848–854; http://dx.doi.org/10.1289/ehp.1510046 Perfluoroalkyl acids (PFAAs) are human-made chemicals found in various products, for example, food items and packaging, pots and pans, and textiles such as carpets, furniture, shoes, and clothing . Specifiin vitro  was established in 1989 and contains self-administered questionnaire data from pregnant women who plan to give birth at the hospital. Most women complete the questionnaire at approximately 12 weeks of gestation. The cohort also contains information about birth outcomes collected by clinical staff (attending midwives) immediately after delivery using a structured birth registration form. Trained research midwives validated birth data until January 2013, and after this date the authors reviewed the registry records. So far, the cohort contains information on > 100,000 women .A biobank was added to the cohort in 2008 and contains blood samples from pregnant women, their partners, and umbilical cord material . Most man = 2,853) we randomly sampled 1,533 women recruited during 2008–2013 . Of these women, 1,507 (98%) had complete data on exposure, birth weight, and covariates and were included in the final study population. Regarding birth length, 1,499 (98%) participants were included, and for head circumference, 1,494 (97%) participants were included in the analyses. Approval was obtained from the Danish Data Protection Agency (reference 2012-41-1288), and the data collection was accepted by the Danish National Committee on Health Research Ethics (reference M-20110054).For this study, women in the cohort were eligible if they donated a blood sample between 9 and 20 completed gestational weeks, gave birth to a live-born, singleton neonate, and were nulliparous. From the women who fulfilled these criteria  . PFAA anz-score), birth length, and head circumference at birth. z-Scores were calculated by standardization of birth weight for gestational age according to the most recent (1996) Scandinavian fetal reference (n = 5) were excluded from the analyses of birth weight along with six participants with missing birth weight.The outcomes available in the cohort included birth weight  to estimate the association between individual PFAAs and continuous birth weight and birth weight n = 11) and level of education (n = 4).We identified covariates to include in the analyses by directed acyclic graphs (DAGs) . The analyses were adjusted for maternal age (continuous), maternal prepregnancy body mass index [BMI (continuous)], and maternal level of education (four categories). Furthermore we conditioned on parity by restricting to nulliparous women. Information on maternal age and parity was available in the birth registration form, and information on BMI and maternal level of education was extracted from the questionnaire. There were no missing values for maternal age. Few values were missing for BMI . Due to previous reports on sex differences concerning the investigated association ]. STATA statistical software version 12  was used for all the statistical analyses.In a secondary analysis, we included gestational age (continuous) in the birth weight model in addition to the other covariates. We did this to compare our findings with the existing literature, even though we are aware of the caveats of adjustment for a potential intermediate . These cociation , we perfFor seven of the measured PFAAs, more than 50% of the samples had concentrations above the lower limit of quantification . LOQ, levels above the LOQ, and distributions of the included PFAAs are listed in Women with exposure levels in the higher quartiles were slightly older than those with exposure levels in the lower quartiles—the median ages were 29 years in the lowest quartiles and 30–31 years in the highest . Maternan = 1,426). Continuous exposure measures of these compounds were not consistently associated with lower estimated mean birth weights.For three perfluoroalkane sulfonic acids  estimated mean birth weights were lower for all quartiles above the first quartile . Only PFNo obvious association was found between PFOA, PFNA, PFDA, and PFUnA and birth weight  regardleRestricted cubic splines of the associations between PFAAs and birth weight are presented in Figure S3. In general these did not identify any clear thresholds nor did they indicate monotonic dose–response patterns.The associations between PFAA exposure and birth weight did not differ substantially between boys and girls for most compounds . For PFNEstimates for the association between PFAA exposures and birth length and head circumference at birth were all close to zero (see Table S3). There was no obvious association between PFAA exposure and gestational age at birth or preterm birth (see Table S4). The levels of PFAAs were similar in samples taken before and after 13 gestational weeks (data not shown), and the exclusion of 67 participants with a blood sample drawn after 13 completed gestational weeks did not change the results (data not shown).Overall, we found weak and inconsistent associations between PFAA exposures and birth weight, birth length, and head circumference at birth. Independent of offspring sex, estimated mean birth weights were lower in quartiles above the lowest quartile of three perfluoroalkane sulfonic acids, without clear monotonic dose–response patterns, whereas PFNA and PFDA tended to be associated with lower birth weight in girls only. However, the sex-specific estimates were less precise than the estimates from the complete population.Quite a few studies have investigated the association between PFAAs and infant size at birth. PFAAs were measured in plasma or serum from maternal blood before conception, during pregnancy, or at birth, or in umbilical cord blood; and exposures were modeled as different continuous or categorical variables, which have made comparison of the results cumbersome. Also, the studies controlled for different factors . Nine stWe studied women who were nulliparous at inclusion, gave birth to a live-born child, provided blood samples, and completed a questionnaire. This may influence the validity and generalizability of our results. Selection bias due to nonresponse may not be very likely since participants were unaware of individual exposure levels (at any time) as well as the outcomes at the time of inclusion. However, it cannot be ruled out that the selection of study participants may have been associated with both exposure levels and the outcomes.A few studies investigated the association between PFAAs and fecundability , miscarrAccurate exposure assessment and the use of multiple exposure scales  were strengths of our study. We chose to use the same continuous exposure scales for all compounds even though an increase of 0.1 ng/mL was a large increase for compounds with low average concentrations and a small increase for compounds with higher average concentrations such as PFOS and PFOA. To ease comparability for the different PFAAs within our study, we also used continuous exposures divided by the interquartile range. We demanded strict laboratory procedures from sampling to the final analysis. Limited time was allowed from blood sampling to processing and freezing, state-of-the-art laboratory equipment was used, and the high performance chromatography–tandem mass spectrometry setup was controlled using internal and external validation and controls. Objectively measured exposures such as PFAA levels are unlikely to be prone to differential measurement error. Because levels of PFAAs decrease throughout pregnancy , we onlyTrained health care professionals systematically assessed the outcomes as part of routine data collection concerning all births at the hospital. Measurement error concerning birth weight, particularly differential measurement error, is unlikely to be of importance. However, birth length and head circumference at birth may be more prone to measurement error, and this might partly explain our close-to-null results for these outcomes.z-scores may be attributable to collider stratification bias .We were able to control for the potential confounders we considered to be most important , including maternal prepregnancy BMI, age, educational level, and parity (by restriction to first-time mothers). Maternal prepregnancy BMI and education were self-reported and may thus be recorded with some error. It is debatable whether the slightly stronger association for PFHxS, PFHpS, and PFOS after adjustment for gestational age, restriction to term births, or modeling of Physiological phenomena in pregnancy, including changes in the maternal glomerular filtration rate (GFR) and plasma volume expansion, may be potentially important confounders if exposures are assessed in late pregnancy or at birth . These pLevels of PFAA compounds are correlated (see Table S2), and different PFAAs are likely derived from similar exposure sources. Biologically, it is possible that different PFAAs share health effects.We found no strong associations between PFAA exposures and birth weight, birth length, or head circumference at birth. In particular, we failed to replicate the association between PFOA and lower birth weight previously shown primarily in populations with higher exposures that were not restricted to nulliparous women. The estimated mean birth weights were lower in quartiles above the reference for PFOS, PFHxS, and PFHpS for all infants and for PFNA and PFDA in girls only. Most of the compounds we investigated have not been studied much, and more studies are warranted.(721 KB) PDFClick here for additional data file.


Cerebral small vessel disease (SVD) is the major cause of vascular cognitive impairment, resulting in significant disability and reduced quality of life. Cognitive tests have been shown to be insensitive to change in longitudinal studies and, therefore, sensitive surrogate markers are needed to monitor disease progression and assess treatment effects in clinical trials. Diffusion tensor imaging (DTI) is thought to offer great potential in this regard. Sensitivity of the various parameters that can be derived from DTI is however unknown. We aimed to evaluate the differential sensitivity of DTI markers to detect SVD progression, and to estimate sample sizes required to assess therapeutic interventions aimed at halting decline based on DTI data. We investigated 99 patients with symptomatic SVD, defined as clinical lacunar syndrome with MRI confirmation of a corresponding infarct as well as confluent white matter hyperintensities over a 3 year follow-up period. We evaluated change in DTI histogram parameters using linear mixed effect models and calculated sample size estimates. Over a three-year follow-up period we observed a decline in fractional anisotropy and increase in diffusivity in white matter tissue and most parameters changed significantly. Mean diffusivity peak height was the most sensitive marker for SVD progression as it had the smallest sample size estimate. This suggests disease progression can be monitored sensitively using DTI histogram analysis and confirms DTI’s potential as surrogate marker for SVD. Cerebral small vessel disease (SVD) causes about 20% of ischaemic stroke, and is the major cause of vascular cognitive impairment, including dementia. Whilst magnetic resonance imaging (MRI) techniques play a crucial role in diagnosis they are also being used increasingly to monitor disease progression and have been proposed as surrogate markers to assess the effects of therapeutic interventions. This latter use is of potential importance in detecting change given that cognitive testing has been shown to be relatively insensitive in measuring longitudinal decline ,2.Conventional MRI hallmarks of SVD include T2-white matter hyperintensities (WMH) and lacunes of presumed vascular origin. However, diffusion tensor imaging (DTI) has been shown to be a more sensitive measure of white matter (WM) damage in SVD detecting abnormalities not only within WMH but also in apparently normal appearing white matter (NAWM) ,4. In crSeveral quantitative measurements can be derived from DTI ,12. MeanThis prospective longitudinal study aimed to determine the sensitivity of different DTI parameters to WM damage over a period of 3 years in a clinically defined cohort of symptomatic SVD patients with MRI confirmation of a corresponding small subcortical infarct as well as confluent WMH. It also used the DTI data to evaluate sample sizes required for clinical trials to demonstrate treatment efficacy, and determine which DTI parameters provide the most statistical power to detect change in such studies.Patients presenting with symptomatic SVD were recruited as part of the St George’s Cognition and Neuroimaging in Stroke (SCANS) study  from strOne hundred and twenty one patients were recruited into the SCANS study ,18,19 an-1 and a proprietary head coil. Patients were neutrally positioned in the head coil using an alignment marker at the nasal bridge to standardise head position. Foam pads and a Velcro strap across the forehead were used to minimise head movement during the scan.MRI scans were performed using a 1.5-Tesla GE Signa HDxt system  with a maximum gradient amplitude of 33 mTm2, matrix = 256x192; II. coronal T1-weighted spoiled gradient recalled echo (SPGR): TR = 11.5ms, TE = 5ms, 176 slices without slice gap, FOV = 240x240mm2, matrix = 256x192, flip angle = 18°, providing 1.1mm3 isotropic voxels; and III. axial single shot spin echo planar diffusion-weighted imaging: TR = 15600ms, TE = 93.4ms, 55 slices without slice gap with isotropic voxels of 2.5mm3, FOV = 240x240 mm2, matrix = 96x96, 8 non-diffusion-weighted images (b = 0 smm-2) followed by diffusion-weighted volumes with diffusion gradients applied (b = 1000 smm-2) in 25 non-collinear directions and the negative of these.The imaging protocol lasted approximately 45 minutes and included the following scan sequences which all provided whole head coverage: I. axial Fluid Attenuated Inversion Recovery (FLAIR): repetition time (TR) = 9000ms, echo time (TE) = 130ms, inversion time (TI) = 2200ms, 28 slices of 5mm thickness without slice gap, field of view (FOV) = 240x240mmNew Segment [3 isotropic voxels, providing tissue class probability maps (TPMs) for WM, grey matter (GM), and cerebrospinal fluid (CSF). These segmentations were used to calculate deformation fields using a diffeomorphic registration algorithm  = 3.03%), Pearson’s intra-class correlation coefficient = 0.98. The inter-rater reliability metrics were: Standard error of mean = 187mm3, mean variability = 5.57% (SD = 3.99%), Pearson’s intraclass correlation coefficient = 0.99. Areas of lacunar damage were manually identified on native space T1-weighted images with reference to the FLAIR images, and segmented using a space-filling algorithm in ITK-SNAP , Pearson’s intra-class correlation coefficient = 0.99. The corresponding inter-rater reliability metrics were: Standard error of mean = 2mm3, mean variability = 4.32% (SD = 4.19%), Pearson’s intraclass correlation coefficient = 0.99.The steps used are detailed in Lambert et al , but are Segment  the FLAIox SPM12 ). Followox SPM12  were gennn et al . The intsnap.org ). Grey sThe regions of lacunes of presumed vascular origin were removed from all tissue segmentation maps and classed as a fifth tissue class. All images were visually inspected to ensure consistent segmentation quality. The similar intensity profile of GM and WMH on T1-weighted images can cause tissue misclassification between GM and WM. To avoid this, the GM and WM maps were corrected using the binarised WMH and lacune of presumed vascular origin segmentations . The NAWwww.fmrib.ox.ac.uk/fsl [2s-1 were considered to contain CSF and excluded).Diffusion-weighted images were pre-processed to remove eddy current distortions using the FSL Linear Image Registration Tool . The poc.uk/fsl . The 8 bc.uk/fsl . The tra−6). Since FA and diffusivity measures are non-normally distributed in WM, we evaluated longitudinal change of the following histogram parameters: median, peak value, peak height, skew and kurtosis. These parameters have also been shown to have associations with cognition in a healthy older adult and SVD population [Using DTIfit in FSL a diffusion tensor model was fitted for each voxel from which tensor-derived FA, MD, RD and AD maps were subsequently calculated . Diffusipulation ,30.Out of the 99 patients included in the current study, for each of the consecutive three year follow ups, scanning sessions were performed on 98, 77 and 71 patients, with DTI respectively available for 99, 96, 74 and 68 patients . DispropDuring follow-up three patients suffered new clinical strokes. Of these one patient had a small cortical haemorrhage which was considered a study endpoint. The other two patients had new small subcortical infarcts and were eligible to remain in the study according to the protocol, one was however unable to do so due to disability and withdrew.2 tests where appropriate in Statistical Package for Social Sciences version 20.0 .Differences between baseline demographics and neuroimaging characteristics of the 99 patients included in the current study and those who did not attend any follow-up MRI were evaluated using Mann-Whitney U and χLinear mixed-effects (LME) models in MLwiN  were uswww.R-project.org) [Sample size estimations were carried out for all DTI parameters using longpower statistical package in R version 3.02 (ect.org) . For theDTI analysis produces many related parameters. To determine whether a more predictive score could be developed by combining these different measures, we also performed principal component analysis (PCA) using SPSS 20.0 to reduce the number of DTI parameters into one component that reflected the underlying variability in the data. PCA was applied to baseline DTI values. Component scores for subsequent time points were calculated using the component coefficients and standardised DTI values based on baseline values. To overcome the multicollinearity issue of highly correlated variables, we chose to exclude RD and AD parameters from the PCA as they can be considered as subparameters of MD. When all candidate variables were included in the PCA we observed problems with multicollinearity (correlation matrix determinant <0.0001). When we restricted variables to those that declined significantly over time in our primary analysis this problem was ameliorated. Principal components were retained if eigenvalues were greater than 1. Promax rotation was applied. Following PCA, LME models were also created for the principal component scores.Study cohort demographics and the volumetric measures of the various tissue class segmentations are shown in There was a highly significant change in most DTI parameters for both NAWM and All_WM with p-values ≤0.001 . FA and There was a change in the shape of the FA histograms over time due to a reduction in FA which manifested as decreased median and peak value, and an increased peak height . This re−6 mm2s-1, p < 0.001; RD: annualised change rate = -7.64×10−6 mm2s-1, p < 0.001) and peak values . Histogram peak height was reduced over time in all diffusivity measures and skew increased.A significant change of most DTI parameters was also observed within regions of WMH . The dirWithin the CSF the MD median, peak height, peak value and kurtosis remained stable over time see . A signiPercentage residual error for each model was highly varied within both All_WM and NAWM. In particular kurtosis of the diffusivity measures had high residual errors: 9.515–42.658% within All_WM, and 12.235–68.440% within NAWM. Residual errors of skew models in the diffusivity DTI parameters were also relatively high. For MD and RD, these errors were larger than the annualised skew change rates.The extracted principal component scores for All_WM and NAWM accounted respectively for 80.6% and 74.9% of the variance in the PCA. Very large annualised change rates were observed . Residual errors were equally large but did not exceed annualised change rates.Our results demonstrate that DTI is sensitive to change in patients with SVD over a relatively short duration of follow-up. Observed changes in DTI parameters were consistent with a progressive degradation of WM ultrastructure showing a decline in anisotropy and increase in diffusivity in WM. However our analysis demonstrates that different DTI parameters show marked differences in the sensitivity to change and errors. We have shown that the most sensitive marker for SVD progression is MD peak height. This finding indicates greater stability of MD values compared to its radial and axial counterparts, as well as sensitivity to change and a good model fit. We also provide sample size estimates, which will be useful in planning clinical trials using DTI as a surrogate marker. It follows that MD peak height has the smallest sample size estimate.Over three year follow-up most DTI histogram parameters changed significantly. Interpretation of longitudinal DTI changes is not always straightforward. Changes in diffusivity histogram distributions are due to increased tissue ultrastructural damage that manifests as increases in diffusivity. This results in higher median and peak value, and a lower peak height as higher diffusivity values are identified with greater frequency. Increases in diffusivity values cause the rightward tail of the distribution to become broader, increasing the positive skew. Also, the related reduction of lower diffusivity values causes the diffusivity histograms to become less peaked and have lower kurtosis. This negative change is observed in MD and RD (All_WM), although it does not reach significance. For the remainder of kurtosis values, in RD (NAWM) and AD, kurtosis increases, significantly in the case of the latter. This finding most likely reflects the instability of AD as a reliable DTI measurement, indicated by the high residual errors in AD kurtosis models. Since AD is the diffusivity in the principal diffusion direction, errors in eigenvalue sorting and inaccuracies in the approximation of the principal diffusion direction using the DTI model will have a large impact on measurement of the AD parameter . High reChanges in the FA histogram distribution are due to reductions in FA that manifest as a lower median and peak value, and a higher peak height due to identification of lower FA values with greater frequency. In turn this causes a greater rightward tail of the distribution (greater positive skew) and a more pronounced peak (greater kurtosis). However, FA histogram parameters were found to have a poor longitudinal model fit with high residual error. This may be due to ambiguity of FA values. In particular, as FA is defined by a quadratic function in three related variables, similar FA values can represent different diffusion tensor  shapes . The depSamples sizes depend on the detected power of observations. Power in turn relies on error, so depends on measurement stability, effect size and in this case magnitude of change. Since scanner upgrades can affect measurement of DTI histogram parameters , their e−6 mm2s-1 in CADASIL [−6 mm2s-1 change found in this study. Charlton et al., [Despite relatively high patient dropout rates which could bias the sample to those with less decline, significant changes were detected in our cohort. The patient group who did not attend follow-up were older and had worse cognitive levels, indicating that such patients may be more vulnerable to decline and consequently an underestimation of actual change in DTI parameters in the study population. Secondly, the use of small histogram bin-widths in our analyses increased noise in measurements of peak value and peak height. A trade-off between sensitivity and noise is applicable when deciding on histogram bin size. We have however shown that annualized change rates of DTI parameter peak value and peak height are small and therefore require small histogram bin widths to enable detection of change. Also, we have generated histograms from WM tissue because SVD predominantly affects the subcortical structures, and in pilot studies we have shown that DTI parameters were sensitive to change in WM over short time periods in SVD . However CADASIL  which is et al.,  on the o et al., . TogetheOur data suggests disease progression in SVD can be monitored sensitively using DTI histogram analysis. This is in line with earlier whole brain DTI histogram in ageing , sporadiApart from being able to detect prospective change MRI markers will have to meet further requirements to fulfil all criteria of a validated surrogate marker ; one of In summary, we observed significant longitudinal change in various DTI histogram parameters in WM in a SVD cohort of patients with symptomatic lacunar stroke and confluent areas of WMH of presumed vascular origin. The reliability and sensitivity of individual DTI histogram parameters as markers of disease progression is however highly variable. Our results suggest MD peak height is the most sensitive marker for detecting ultrastructural brain tissue damage in SVD. Future studies investigating progression of SVD and the use of DTI as a surrogate disease marker are needed and should focus on the relationship between the clinical outcomes of SVD and imaging markers.S1 Dataset(XLS)Click here for additional data file.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.


The risk of preterm birth among mothers who perceived their neighborhood as of poor quality was about 30% greater compared to mothers who perceived their neighborhood as of good quality; the risk was 12% greater among mothers with low resilience compared to those with high resilience. Effects of neighborhood quality were not modified by maternal resilience. The findings suggest that mothers’ perception of neighborhood quality and resilience are associated with the risk of preterm birth. Further research should explore whether initiatives aimed at improving neighborhood quality and women’s self-esteem may improve birth outcomes.We examined the associations of mothers’ perception of neighborhood quality and maternal resilience with risk of preterm birth and whether maternal resilience moderated the effect of neighborhood quality perception. We analyzed data from 10,758 women with singleton births who participated in 2010–2012 Los Angeles Mommy and Baby surveys. Multilevel logistic regression models assessed the effects of mothers’ perception of neighborhood quality and maternal resilience on preterm birth (yes/no), controlling for potential confounders and economic hardship index, a city-level measure of neighborhood quality. Interaction terms were assessed for moderation. Mothers’ perception of neighborhood quality and maternal resilience were each uniquely associated with preterm birth, independent of potential confounders ( Preterm births, defined as births that occurred before 37 weeks of pregnancy, are a serious health concern. Infants born preterm are at a higher risk of early death and lifelong neurologic and cognitive defects than those born later in pregnancy . The preA considerable amount of research has been done to identify and understand risk factors for preterm births, including behavioral risk factors and pre-pregnancy health conditions ,4. VarioThe quality of the neighborhood environment can also be a significant source of stress. There has been increasing investigation on the influence of environment and neighborhood on an individual’s health ,6,7. TheA number of epidemiological studies have investigated the association of mothers’ pre-pregnancy health conditions and psychological state with pregnancy outcomes ,9. SuppoIn this study, we aimed to investigate whether neighborhood quality and maternal resilience are associated with the risk of preterm birth using a large population-based sample of mothers from Los Angeles County. This research was performed at the Los Angeles County Department of Public Health. Local public health departments may be better equipped and trained to improve maternal resilience, by designing appropriate interventions, compared to neighborhood safety and cleanliness. Hence, hypothesizing that women with high resilience might be better able to overcome the effects of a disadvantaged neighborhood, we also aimed to investigate whether maternal resilience moderates the association of neighborhood quality with preterm birth. Data for this study were obtained from the 2010 and 2012 Los Angeles Mommy and Baby Surveys (LAMB), combined with information from birth certificates. LAMB is a cross-sectional, population-based survey conducted by the Los Angeles County Department of Public Health (LADPH) every two years since 2005 . The LAMLAMB data are used for surveillance and research to monitor, evaluate and improve maternal and child health in Los Angeles County. LAMB employs a stratified random sampling scheme based on Service Planning Areas (SPAs), race/ethnicity and maternal age. African American women and women less than 20 years old were oversampled, and sample weights were assigned to correct for oversampling and allow the representation of population estimates. The response rates for LAMB were 57% in 2010 and 62% in 2012. Birth certificate data of the respondents were linked to their LAMB survey data by LADPH.The project was approved by the California Committee for the Protection of Human Subjects. Informed consent was obtained from all participants.vs. full-term) were also omitted. The study only included singleton births, and hence, twins or other multiples were also excluded. Our study sample consisted of 10,758 Los Angeles County resident mothers who gave birth to a live-born singleton in 2010 or 2012 and who participated in the 2010 or 2012 LAMB survey. Respondents who lived in the neighborhood where they spent most part of their pregnancy for less than 1 year and those who were missing information on how long they had lived in the neighborhood were omitted from the analysis. Respondents who were missing information on birth outcome (preterm The outcome for this study was preterm birth (yes/no), defined as a birth that occurred in less than 37 weeks of pregnancy . InformaThe two main independent variables of interest were neighborhood quality and maternal resilience.(1) Perceived neighborhood quality: Mothers’ perception about the quality of her neighborhood was assessed using five questions in the LAMB survey that were derived from items used in the Los Angeles Family and Neighborhood Survey (L.A.FANS)  and in t(2) Maternal resilience: The survey included five questions that asked mothers how strongly they agreed with statements about their self-esteem and perception that they can achieve their goals or complete tasks and control the events affecting them. These questions were based on a modified previously-validated Rosenberg self-esteem scale  and PearPotential confounders were selected as control variables for the analysis. These covariates included participant sociodemographic characteristics, medical risk factors and health behavior risk factors.(1) Sociodemographic factors: Sociodemographic factors were maternal race/ethnicity , maternal age , maternal education , marital status during pregnancy  and insurance before pregnancy . Sociodemographic information was obtained from the survey data.(2) Medical risk factors: A pre-pregnancy health conditions indicator variable was coded as “yes” if the respondents reported any of the following conditions before pregnancy in the survey: asthma, hypertension, diabetes, anemia, heart problems or problems with gums or teeth. Otherwise, it was coded as “no”. (3) Health behavior risk factors: Adverse health behaviors, such as smoking (primary and passive smoking) and substance use during pregnancy, were also included as potential confounders. Smoking and passive smoking were coded as “yes” if respondents reported smoking or exposure to second-hand smoking during pregnancy in the survey, respectively, and “no” otherwise. Substance use was coded as “yes” if the respondent indicated in the survey using marijuana, amphetamines, cocaine or tranquilizers during pregnancy and “no” otherwise. (4) Objective measure of neighborhood quality (neighborhood-level data): The neighborhood-level variable used in this study was the economic hardship index (EHI), developed by the Los Angeles County Department of Public Health. The economic hardship index value is calculated for each city in Los Angeles County with a population larger than 10,000; for the City of Los Angeles, it is calculated for each LA City Council District. The EHI is based on six census tract-level variables: (a) per capital income; (b) percent of persons with less than a high school diploma for a population 25 years and older; (c) percent of persons at less than 200% of the federal poverty level; (d) percent of civilian population over the age of 16 that was unemployed; (e) percent of the population under the age of 18 or over the age of 64; and (f) percent of occupied housing units with more than one person per room. Scores on the index of 1–100 were generated, with a higher score representing a greater level of economic hardship. Details on how the economic hardship index is calculated are available elsewhere . We cateWe summarized the characteristics of our study population using both raw and weighted frequencies, the latter obtained using survey weights. Bivariate associations between the independent variables  and the dependent variable (preterm birth) were assessed using chi-square tests using the sampling weights. We then investigated the association of neighborhood quality and maternal resilience with preterm birth using multilevel logistic regression. The model included the neighborhood quality and maternal resilience indicators and controlled for sociodemographic factors, pre-pregnancy conditions and health behavior risk factors during pregnancy. The model included a random intercept for neighborhood and economic hardship index as the Level 2 (neighborhood level) variable. To investigate the moderation of the effect of neighborhood quality by maternal resilience, we tested an interaction term between these variables. Sampling weights were used in the regression models.Respondents excluded from the analysis due to missing data on one or more variables were compared to respondents included in the analysis using chi-square tests to assess potential bias due to missing data.All analyses were conducted in SAS .There were a total of 13,436 respondents to the 2010 and 2012 LAMB surveys. After applying the exclusion criteria, 10,758 respondents were included in this study. This corresponded to a weighted frequency of 213,083 mothers in Los Angeles County.Bivariate analysis  indicatep-values < 0.01). The interaction term between these two variables was not statistically significant  and, hence, was dropped from the model. According to the final model, controlling for all potential confounders, mothers who perceived their neighborhood as that of poor quality had 1.3-times higher risk  of having a preterm birth outcome compared to those who perceived their neighborhood as that of good quality. Mothers with low resilience had 1.12-times higher risk  of having a preterm birth outcome compared to those with high resilience.p-value <0.05), implying that there was additional variation in preterm outcomes at the neighborhood level that was not explained by the economic hardship index.African-American, Hispanic, Asian/Pacific Islander and Native American women had higher risk of preterm birth compared to their white counterparts. Unmarried women also had a higher risk of preterm births compared to their married counterparts. Smoking and substance use during pregnancy were associated with increased risk of preterm birth. Unexpectedly, secondhand smoke exposure was associated with lower risk of preterm birth, controlling for other variables. The variance of the random intercept was non-zero . Results of these comparisons are summarized in Overall, 21% respondents  were excluded from the analytic dataset due to missing data. About 50% of the excluded respondents (n = 1152 out of 2289) were missing information on the economic hardship index due to sampling from unincorporated communities in Los Angeles County. Chi-square tests comparing included and excluded participants on maternal race/ethnic group, education, marital status, insurance status, passive smoking and substance abuse were statistically significant. However, chi-square tests on the key variables of interest, preterm birth, neighborhood quality and maternal resilience, were non-significant   and in tOur study has several strengths. We had a large and population-based sample for this study, and we also systematically controlled for many potential confounders in our statistical models. However, we cannot rule out the possibility of unmeasured confounding. In Los Angeles County, about 10% of births, corresponding to about 10,000 births each year, are preterm. Infants born preterm are at higher lifelong risks of neurologic and cognitive defects [Our study supports the premise that interventions designed to increase maternal resilience and to improve neighborhood quality in terms of safety and cleanliness may be beneficial to improve birth outcomes. Though it is difficult to change neighborhood quality dramatically without policy implementations, interventions to increase maternal resilience may be more easily designed and implemented and may have other beneficial consequences. Our results suggested that controlling for potential confounders and neighborhood socioeconomic characteristics, perceived neighborhood quality and maternal resilience were each significantly associated with the risk of preterm birth. We did not find evidence of maternal resilience moderating the association of neighborhood quality and risk of preterm birth. To help us design more effective interventions, further studies are needed to investigate the relationships among neighborhood quality, maternal resilience and preterm births and to elucidate the underlying mechanisms.