The lasting or lifelong effects of under-nutrition will depend on the period in the development at which it occurs. The clues that led Barker to his conclusions started to be discovered when he was studying the temporal trends in the incidence of ischemic heart disease in England and Wales. Examining data found in The Hertfordshire records, collected in the beginning of the last century, he found that the rates of mortality by ischemic heart disease was much higher in children born in less affluent counties and mostly in those with low birth weight. After his initial findings a myriad of diseases have been found to be linked to low birth weight and under-nutrition in utero and in the neonatal period. These diseases were then nominated adult diseases with fetal origin. Epidemiological studies that led to these findings suggest that in utero and early postnatal life have critical importance for long-term programming of health and disease, opening unique chances for primary prevention of chronic diseases.During our phylogenetic evolution we have selected genes, the so called thrifty genes, that can help to maximize the amount of energy stored from every consumed calorie. An imbalance in the amount of stored calories can lead to many diseases. In the early 80’s the distinguished English epidemiologist David Barker, formulated a hypothesis suggesting that many events that occur during the intrauterine life and early in infancy can influence the occurrence of many diseases that will develop in adulthood. This theory proposes that under-nutrition and other insult or adverse stimulus  In order to understand what we weight from our intrauterine life until adulthood, we must understand our genes. It is supposed that at least 24.000 genes constitute the human blueprint and that over 250 of these genes may help determine our weight .About 40.000 years ago, somewhere in the world, a Paleolithic couple emerged to become the great, great, great… grandparents of us all. Their genes still inhabit our cells, and we continue to pass them from one generation to the next, and these genes still shape our metabolic pathways. We must look to our Paleolithic ancestors to understand the modern-day problems of obesity, diabetes and many other diseases. We must look to these genes to know why the environment we have created is so aggressive to our health. We must understand how and why the genes that were advantageous in the past are so deleterious now .Our ancestors were nomads. They used to travel long distances in search of food. The food sources were unreliable and no one ever knew exactly where or when they would get the next meal. When food was present, especially like fat and protein of animal origin, to store calories within the body was a very wise strategy .Paleolithic men were possibly lean, muscular and strong. Their bodies evolved to withstand the danger that was everywhere. They used to have vigorous physical activity and insufficient food was a constant risk .Women like the men used to be physically active and in order to supplement what men brought back home, they gathered nuts, berries, fruits, vegetables and roots. Obesity supposedly did not exist, because the food supply was so uncertain .We cannot be certain, but possibly the Paleolithic diet was approximately 30 percent protein that came from fish and meat. We can certainly assume that the mammals our ancestors ate were also lean; they probably did not live in feedlots or graze on carefully managed pastures. They had to exert themselves to obtain food and to avoid becoming the meal of some other animal. So like the hunters who hunted them, their body composition was largely composed by muscles .Our ancestors’ diet possibly consisted of up to 100 grams of fiber per day, what is 5–10 times higher than is typical today. Fat corresponded to approximately 20 percent and was mostly unsaturated since it used to come from nuts and seeds. Since the meat was also lean, Paleolithic diet was minimally composed by saturated fat [Paleolithic men and women did not live long, possibly less than 20 years. If they survived birth and infancy, most died in what we consider today young adulthood. They were vulnerable to famine, predators, accidents and infections; the women faced all this plus the risk of childbirth. We can certainly assume that our ancestors did not have health problems obesity-related that plague us today. Because of their low fat intake, their blood vessels were probably free of fat deposits and stroke; heart attacks and high blood pressure were possibly rare. Diabetes and obesity were not known those days. Also, by not living so long, they would not have time to develop chronic diseases .The genes of our Paleolithic ancestors evolved for people who spent their days in constant physical activity and whose diet was low in calories and in saturated fat. Although, evolution selected genes that could support times of a poor food supply of a poor food supply, long winters and long times of recurrent droughts. These genes were called thrifty genes because they helped to maximize the amount of energy that could be obtained and stored from every consumed calorie ,2.One possible mechanism for accomplishing this was insulin resistance (IR) that was an adaptive condition for babies, before and after birth, in order to use few calories more efficiently. In times when food was more abundant, these genes would enable these babies to eat more and stock body fat for the future hard times that would certainly come. When food was scarce these genes would preserve those fat stores, slowing down metabolism and keeping the body’s energy reserves ,2.Thrifty genes were advantageous for life in the Paleolithic era. About 10.000 years ago, the world began to change. Many humans developed agriculture, domesticated animals, left behind their nomadic way of life, settled down and developed cities and civilizations. Famines became less frequent and the nutritional environment became altered. Humans started to eat more grains and consequently less fish, fruits and vegetables. Animals started to be raised in enclosed spaces and also became fatter. The saturated fat they contained was less favorable to the human metabolism and cardiovascular system .It seems that these thrifty genes became less important in societies with better climate and abundant supplies. This helps to explain why obesity and diabetes for example, are more common in some parts of the world than in others ,2.In the 1980’s, Barker developed a hypothesis according which many nutritional events that occur during the intrauterine life and early in infancy will influence the development of adult diseases. This became the so called Barker hypothesis .Lucas, proposed the term “programming” to describe the process by which an adverse event happening at a critical period of development, has long lasting or lifelong significance . Fetal pin utero and during infancy can permanently change the body’s structure, physiology and metabolism. The lasting or lifelong effects of under-nutrition will depend on the period in the development at which it occurs. In early gestation it will reduce body’s size permanently, whereas in late gestation it will have deep effects on body form without necessarily reducing body size. Fetuses and neonates that are rapidly growing are more vulnerable to under-nutrition. These effects include altered gene expression, reduced cell numbers, imbalance between cell types, altered organ structure, pattern of hormonal release and hormonal responses [Barker’s hypothesis suggests that under-nutrition and other insult or adverse stimulus esponses . Thus, tesponses .The clues that led Barker, a distinguished epidemiologist to formulate his hypothesis started to be discovered when he was studying the temporal trends in the incidence of IHD in England and Wales ,6.th century, and in the present days it has been growing in the so called developing countries such as China, India, Russia and in many eastern European countries. Such abrupt changes, in a so short time frame, could not be explained by genetic changes, and then the attention of the scientists was directed to the existing lifestyle in the industrialized countries. The relationship of IHD with obesity, smoking habit, high cholesterol levels and stress among many other factors have been well established [The incidence of IHD increased rapidly in the western world in the beginning of the 20ablished ,6.In 1977, Forsdahl has found considerable variations in the rates of mortality from IHD in twenty Norwegian counties. He has suggested that these variations could not be explained by the current differences in standard of living existing then. Such differences did exist in the past as was shown by large variations in infant mortality. A significant positive correlation has been found between the county age-adjusted mortality from IHD in people aged between 40 and 69 years and county’s infant mortality relating to the early years in the same cohorts. His findings suggested that great poverty in childhood and adolescence followed by prosperity, was a risk factor for IHD [Studying the geographic distribution of mortality by IHD, Barker has found that although the rise in IHD in England and Wales has been associated with increasing prosperity, paradoxically, mortality rates by IHD were higher in the least affluent areas. A strong geographical relation between IHD mortality rates in 1968–78 and infant mortality in 1921–25 was observed. IHD was found to be strongly correlated with both neonatal and postneonatal mortality rates. These findings led him also to suggest that poor nutrition in early life increases susceptibility to the effects of an affluent diet .in utero and in early infancy [Barker concluded then that under-nutrition in women in childbearing age could be the origin of high rates of IHD in the next generation, since it would impair a woman’s ability to nourish her baby  infancy ,6.In order to test the hypothesis that IHD is programmed in utero, it was necessary to study people now, in middle and late life whose early growth had been recorded somewhere. Barker then undertook a search for medical records of babies born in the early 1900s, with the staff from the Medical Research Council of Britain. They searched archives and hospital record departments throughout the country. Many were found; some were in large collections preserved for many years, some had no more then a few hundred records that were kept by a clinic or a midwife. Some were found in lofts, sheds, garages, boiler rooms or flooded basements. Finally, in Hertfordshire, a county localized in the East region of England, just north of London, the appointments made by Ethel Margaret Burnside, the first county’s chief health visitor and lady inspector of midwives were found. She set up an army of trained nurses to attend women in childbearing age and to advise mothers about their babies health .From 1911 onwards, when a woman in Hertfordshire had a baby, she was attended by a midwife that visited her home at regular intervals to get information about the baby’s health and development. The weight was recorded at birth and at one year of age, when visits ceased. From 1923 onwards the health visitors continued their visits until the child was five years old. The ledgers containing these information were maintained until 1945. They were found by the Medical Research Council in 1986 [With the data found in Hertfordshire ledgers, Barker used records from England’s National Health Service to trace about 16.000 men and women who had been born in this county between 1911 and 1930. He then matched information about their current health status to the infant data that were collected by Burnside’s nurses. In 1989 when his study was published, 3.865 people had already died with ages ranging from 20 to 74 years. He observed that the mortality by IHD is almost two times more prevalent in those that had a birthweight ≤ 2.500 g when compared to those who had a birthweight ≥ 4.000 g. Barker discovered that men who had been small at birth, and who were still small at age one, were at the highest risk of presenting IHD. The mortality rates by any other disease had no relation to the birthweight [Subsequent research throughout the world, has found similarly strong associations between LBW and IHD -10.The ‘thrifty phenotype’ hypothesis was proposed based on studies which showed that individuals who had a LBW  have an increased risk of developing symptoms of the metabolic syndrome (MS), T2D and cardiovascular diseases (CVD) later on . This hyA small for gestational age (SGA) is a full term baby who is under 2.500 g at birth or born with a birth weight and/or length under two standard deviations (2 SDs) for the gestational age and sex of the population . The detThe SGA babies can have their birth weight (SGA-w) affected, their birth length (SGA-l) or both (SGA-w/l). These subgroups achieve final height in different ways. SGA-w born children are mostly likely to achieve catch-up growth after the second year of life, while SGA-w/l children more frequently remain short in adulthood .A growth retardation is a failure that can occur during the intrauterine development and is called intrauterine growth retardation (IUGR). If this condition is detected, both mother and fetus should undergo adequate monitoring by fetal biometry and doppler ultrasonography of uterine and fetal blood vessels .The general incidence of SGA newborns is 3-10% -18. In aMost patients born SGA do not have a clear etiology for this condition to happen. Nevertheless, several maternal and fetal conditions have been identified as causative factors for the birth of a SGA baby.Maternal factors can be related to insufficient substrate supply to the fetus during development due to many different causes such as reduced maternal food intake, maternal systemic diseases such as HT and diabetes, periodontal disease, abnormal placental function that can lead to an impaired utero-placental blood supply or disruption of the placental transfer, abruption, infarction or mal-development of the placenta. The majority of these factors can influence growth during the last trimester of pregnancy and result predominantly in IUGR that refers to poor growth of a baby while in the mother’s womb during pregnancy -23. OtheThe exposure of the fetus to a toxic intrauterine milieu caused by tobacco, alcohol consumption or illicit drugs abuse increase the risk of SGA or IUGR births. Smoking during pregnancy has the most significant influence with a relative risk of 3.24 ,25.Several fetal factors are related to the birth of a SGA baby, like some chromosomal anomalies such as gonadal disgenesy, Edward Syndrome, Turner Syndrome, Down Syndrome and Prader-Willi Syndrome .The thrifty phenotype seems to be strongly associated with the birth of a SGA baby. Several mechanisms have been proposed to explain growth retardation of the fetus and the infant. The growth is assumed to be altered both quantitatively and qualitatively by a poor nutritional environment. Metabolic disturbances depend on the period of gestation in which a famine affected the mother and the children, as a Dutch SGA study showed in examining the population who suffered from famine during the Second World War ,27. If fHow can it matter fifty or more years late that a person was born small? Nowadays, there is compelling evidence linking epigenetic factors to many human diseases. Epigenetic factors, by different types of reactions, could mediate the interplay between genes and environment resulting in activation or repression of genetic transcription, or even silencing the genetic transcription. The most important epigenetic reactions affecting genetic transcription are acetylation and methylation. These reactions occur mainly in the tail of histones that are proteins where DNA is wrapped. Brownlee et al. have demonstrated in human aortic endothelial cells, that excessive concentration of reactive oxygen species (ROS) can induce monomethylation of lysine from histone 3 increasing the expression of the subunit p65 of nuclear factor kappa beta. This reaction is responsible for the increased transcription of vascular cell adhesion molecule 1 and monocyte chemoattractant molecule 1 that are both related to diabetes, hypertension and other components of the MS ,31.Plagemann et al., have recently demonstrated in animal models that the neonatally acquired adipogenic and diabetogenic phenotype can probably be caused, at least in part, by over-nutrition in pre-and/or neonatal period, that can lead to alterations of DNA methylation patterns within the promoter regions of genes whose products are involved in the hypothalamic regulation of appetite, body weight and metabolism. In the promoter region of proopiomelanocortin (POMC), the most important anorexigenic neurohormone, neonatally overfed rats develop hypermethylation of activating transcription factor binding sites, in parallel with hypomethylation at an inhibitory transcription factor binding site. The promoter region of the hypothalamic insulin receptor gene promoter was found to be hypermethylated. These studies suggest that perinatal programming of long-term increased obesity and diabetes risk due to neonatal over-nutrition may occur via altered methylation patterns of the promoter regions of central nervous body weight-regulating neuropeptides and receptors -34.During the newborn period SGA babies present increased risk of hypoglycemia, hypothermia, hypercoagulability, hyperbilirubinemia, hypotension, necrotizing enterocolitis, respiratory distress syndrome, lower Apgar scores, umbilical artery acidosis, more intubations and complications during delivery and approximately 20 times increased risk of neonatal death than babies born with an appropriate for gestational age (AGA) weight ,35-37.In the first two years of life, about 90–95% of children born SGA present catch-up growth . More thIn the childhood years, about 10% of children born SGA do not achieve catch-up growth after the second year of life and remain short (≤ 2 SDs) during childhood, adolescence and adulthood ,41. The Children born SGA seem to have modest independent effects on learning, cognition, and attention in adolescence . They alChildren born SGA present early and rapid start of puberty; the amplitude of pubertal spurt is small, and they reach their final height earlier than children born with AGA. Girls have an advanced menarche by 5–10 months and boys have more genital alterations .After Barker’s findings of the strong associations between LBW and IHD it was suggested that many diseases of adulthood could have a fetal origin. Many subsequent studies have shown the association between LBW and a higher risk of developing several adult diseases.In 1976, Ravelli et al., have conducted a historical cohort study of 300.000 19-year-old men exposed to the Dutch famine of 1944–45 and examined at military induction. They have found that outcomes were opposite depending on the time of exposure. During the last trimester of pregnancy and the first months of life, exposure to famine produced significantly lower obesity rates, suggesting that nutritional deprivation affected a critical period of development for adipose-tissue cellularity. During the first half of pregnancy, however, exposure resulted in significantly higher obesity rates consistent with the inference that nutritional deprivation affected the differentiation of hypothalamic centers regulating food intake and growth [Many other conditions have been identified such as an increased risk of T2D ,46,47 anEpidemiological evidence of this casual relationship has been extended to many other diseases such as higher risk of breast cancer ,70, end-The phenotype that seems to be more strongly associated to higher risks of adult diseases is LBW followed by a fast catch-up growth -86.A clear phenomenological association has been demonstrated by many epidemiological studies between LBW and increased risk later in life, for many diseases such as IR, mortality by IHD, MS, T2D, CVD, HT, dyslipidemia, obesity, breast and testicular cancer, end-stage renal disease, osteoporosis, spontaneous hypothyroidism, adult asthma and hearing loss, cardiac hypertrophy, depression, liver cirrhosis, schizophrenia, polycystic ovary syndrome, precocious pubarche, hypospadias, cryptorchidism, low scores of alertness, mood instability, significant differences in academic and professional achievement. Probably, perinatally acquired alterations of DNA methylation patterns of gene promoters of central nervous regulators of body weight and metabolism play a key role in mediating these relationships. In conclusion, under-nutrition during neonatal life plays a critical role, beyond prenatal development, in the long-term programming of health and disease. This opens a variety of opportunities and challenges to primarily prevent chronic diseases such as stature deficits, endocrine, metabolic and neurodevelopmental disturbances during childhood and several diseases as those above mentioned, during adulthood.This should be appropriately considered in future health care policies as well as research programs. Pre and neonatal under-nutrition should be avoided to prevent long-term deleterious consequences. Further studies are suggested to evaluate epigenomic mechanisms such as alterations of DNA methylation, that potentially underlie the increased risks for all these diseases.IR: Insulin resistance; LBW: Low birth weight; T2D: Type 2 diabetes; HT: Hypertension; IHD: Ischemic heart diseases; MS: Metabolic syndrome; CVD: Cardiovascular disease; SGA: Small for gestational age; SGA-w: Small for gestational age with low birth weight; SGA-l: Small for gestational age with short length; SGA-w/l: Small for gestational age with low birth weight and length; IUGR: Intrauterine growth retardation; ROS: Reactive oxygen species; POMC: Proopiomelanocortin; AGA: Appropriate for gestational age.Both authors declare that they have no competing interests.CAN and MBG drafted, reviewed and edited the manuscript. Both authors read and approved the final manuscript.


Preterm birth has the highest mortality and morbidity of all pregnancy complications. The burden of preterm birth on public health worldwide is enormous, yet there are few effective means to prevent a preterm delivery. To date, much of its etiology is unexplained, but genetic predisposition is thought to play a major role. In the upcoming year, the international Preterm Birth Genome Project (PGP) consortium plans to publish a large genome wide association study in early preterm birth. Genome-wide association studies (GWAS) are designed to identify common genetic variants that influence health and disease. Despite the many challenges that are involved, GWAS can be an important discovery tool, revealing genetic variations that are associated with preterm birth. It is highly unlikely that findings of a GWAS can be directly translated into clinical practice in the short run. Nonetheless, it will help us to better understand the etiology of preterm birth and the GWAS results will generate new hypotheses for further research, thus enhancing our understanding of preterm birth and informing prevention efforts in the long run. In the upcoming year, the Preterm Birth Genome Project (PGP), an international consortium of investigators examining the genetics of preterm birth , plans tGenome-wide association studies are designed to identify common genetic variations that are associated with certain health outcomes or diseases. Unlike the search for highly penetrant disease-causing gene mutations such as those underlying sickle cell anaemia and Tay-Sachs disease, GWAS attempt to identify single nucleotide polymorphisms, also known as SNPs, that are not strictly disease causing but rather increase or decrease one’s risk of disease. Highly penetrant genetic disorders are caused by a single mutation or a few genetic variants at most, whereas complex or multifactorial diseases are influenced by many genetic variants as well as environmental factors. Thus a GWAS is inherently searching for genetic variation that does not fit the model of a rare mutation leading to disease; rather it is searching to identify common genetic variation that contributes to the risk for disease. Such an endeavour adds many layers of complexity in terms of both carrying out GWAS as well as interpreting the results.Of the three billion base pairs of the haploid human genome, several million contain individual DNA sequence variants or alleles . SNPs arThe goal of a GWAS is to identify particular SNPs in the genome that are associated with increased risk for or protection from disease. Common variation is generally present in greater than one percent of the population . As mentThe results of a GWAS provide a mechanism for generating further hypotheses to better understand biology, pathophysiology and disease causation. They provide a clue as to where to look amongst the more than three billion base pairs making up the genome to identify important genetic regions, genes, and potential mechanisms. Several publicly available databases exist that list all GWAS studies and their findings published to date Table .DNA for a GWAS can be collected from multiple sources. These include maternal and/or fetal blood, saliva and blood spots. Commercially available high-throughput genotyping platforms (Affymetrix and Illumina) are used for the genotyping of genomic DNA. Currently, these so-called SNP arrays can genotype over 5 million SNPs at the same time. SNP assays rely on the biochemical principle that nucleotide bases bind to their complementary bases (adenine binds to thymine and cytosine binds to guanine) . FragmenOne important concept to consider is linkage disequilibrium or LD. As mentioned previously, this is the non-random association of alleles at two or more loci. Certain combinations of alleles or genetic markers occur more or less frequently together in a population than would be expected from a random formation of haplotypes (series of SNPs close together in the genome) from alleles based on their frequencies. Two SNPs that are in strong LD may therefore serve as proxies for one another: genotyping one of the SNPs gives nearly complete information regarding the genotype of the other SNP. This explains why an array that genotypes 5 million SNPs effectively actually assays a larger proportion of human genetic variation than represented on the array. For maximum advantage, the current arrays are specifically designed to detect SNPs that correlate with, or tag, a large number of other SNPs in the human genome. The work of the International HapMap Project largely facilitated this concept . GeneralPreterm birth is defined as birth before 37 completed weeks of gestation (WHO guidelines) and its rate has risen alarmingly over the past twenty years. After peaking in 2006 at 12.8, the preterm birth rate in the United States was reported at 12.2% in 2009, the most recent year for which data are available -12. Posset al. [The majority of preterm deliveries are idiopathic preterm births and preterm births due to preterm premature rupture of fetal membranes. In both cases, much of the etiology is unknown . While met al. . The leaet al. ,17. Furtet al. . EvidencThe most common design of a GWAS is a case-control study in which a large number of DNA samples from cases and controls are analyzed to look for SNPs that are associated with the disease or condition under study. A generally accepted sample size of 1000 cases and 1000 controls is likely adequate for many GWAS, however the required sample size depends on many factors including the prevalence of the disease and the effect size of the alleles. As in any case-control study, most important to the success of the study is selecting cases that meet a standard and consistent definition of the condition under study. This is a particularly challenging issue in preterm birth research as the phenotype of preterm birth can be quite complex to define. At its simplest definition, preterm birth is defined by the World Health Organization as birth before 37 weeks gestation. But beyond that, the definition becomes much more complex. Is late preterm birth, defined as 34 0/7 to 36 6/7 weeks, the same phenotype as very preterm birth at < 32 weeks? Is a preterm birth that follows chorioamnionitis and preterm premature rupture of the membranes the same phenotype as a preterm birth that follows preeclampsia and a placental abruption, even if they both occur at 28 weeks gestation? While challenging for preterm birth researchers, the goal is to identify as clear and consistent a phenotype as possible. For the purposes of many studies, spontaneous singleton preterm birth is the phenotype of interest and thus multiple gestations, fetuses with birth defects, and major maternal medical complications such as hypertension are excluded.Selection of controls must be carried out such that controls come from the same population as the cases and they must be similar in every way to the cases other than the occurrence of the disease. This is generally accomplished by identifying term controls from the same labour and delivery floors where the cases are identified. Furthermore, it is important that as much demographic and environmental risk data are collected about the study subjects, so that they can be considered and controlled for in the final analyses.The use of genome wide analysis is a very powerful research tool. It can be an important first step in discovering the genetic variations that are associated with preterm birth. Analytic challenges in the interpretation of findings from GWAS however require technical and analytic expertise and software designed to carry out such analyses ,20. The p-value of less than 5 x 10 -8 is considered significant in a GWAS. This p-value threshold is for 1 million SNPs. It roughly approximates a p-value of less than 0.05  when doing one million comparisons. Mathematically, this can be calculated as 0.05 / 1,000,000 = 5 x 10 -8. This is known as a Bonferroni correction, a conservative statistical method to counteract the problem of type I error  in multiple comparisons.There are many challenges to interpreting the findings of a GWAS. Significant findings need to be interpreted in the context of the million comparisons that occur in a GWAS. In order to handle the multiple comparisons, a Population stratification is another major challenge in interpreting GWAS. Population stratification captures the idea that the study identifies a variant (SNP) associated with a characteristic of a population that is associated with the disease, not the disease itself. The SNP of study may have significantly different allele frequencies in two different populations and the frequency of these populations may differ between the case and control group. This induces an association of the SNP with case-control status when it is actually only associated with the population differences between cases and controls. One way to assure that the association between the genetic variant and the disease outcome is actually robust, therefore, is to replicate the finding in a second study of subjects from a different racial / ethnic background. Many journals indeed require replication of findings before publishing GWAS. In addition, computational methods are also available to correct for population stratification in the analysis of a GWAS. Thus far, most GWAS are conducted in populations from European descent. It is important to select a strict and consistent phenotype, and therefore the choice of one particular population is often made. Whether the findings of many of these studies are generalizable to non-European populations is largely unknown.et al. illustrate, one model for using gene environment interactions is targeting environmental interventions such as smoking cessation programs to individuals with specific genetic variants [In complex conditions like preterm birth that are known to be multifactorial, which means they are influenced by both genetic and environmental factors, GWAS will likely only tell part of the story. Demographic and environmental factors may be as important as genetic factors in the etiology of preterm birth. The question remains therefore, how can we best integrate environmental data such as smoking data and stress with the GWAS findings? And what if, as in the case of human height where 20 SNPs where found to explain only approximately three percent of the variation in human height , geneticvariants .Studying pregnancy adds another layer of complexity: there are two patients – mother and newborn – and three genomes to consider: the maternal, paternal and child’s. Integrating genome wide data across three individuals in order to identify the etiology of a complex birth outcome such as preterm birth is a challenge that continues to require new methodologies and continued research.We are hopeful that GWAS will identify regions of the genome associated with preterm birth. They can then serve as a useful tool for researchers to learn more about the basic pathophysiology of preterm birth and the pathways leading to preterm labor. Furthermore, as in the case of many complex disease conditions, there is the promise that risk prediction profiles could be identified in which a number of genetic variants in the aggregate can help assess risk . While tGWAS will not lower rates of preterm birth in the short run. In fact, some critics of GWAS suggest that they have not provided as much information as was hoped. Critics suggest that the genetic variation underpinning many disease states will be found by identifying in a number of rare variants, not common variants, and thus inquiry via GWAS will not likely lead to useful information ,24. But,What is clear, however, is that GWAS in the area of preterm birth will add new information regarding genetic variation and risk to the research arena surrounding preterm birth. They will likely help us learn more about the fundamental biology of preterm birth and the biology of its causation, not its symptoms. GWAS will contribute to our ability to assess personalized risk for preterm birth and hopefully guide pharmacogenomic interventions. In an area such as preterm birth, where the public health burden is tremendous and the clinical interventions are scarce, GWAS will enhance scientific inquiry by providing new ideas and data in an area that is rich for discovery.The authors declare that they have no competing interests.SD and IC contributed equally to the preparation of the manuscript.


Although most pregnancies after IVF result in normal healthy outcomes, an increased risk for a number of obstetric and neonatal complications, compared to naturally conceived pregnancies, has been reported. While there are many studies that compare pregnancies after assisted reproductive techniques with spontaneously conceived pregnancies, fewer data are available that evaluate the differences between IVF and ICSI-conceived pregnancies. The aim of our present study was, therefore, to compare obstetric and perinatal outcomes in pregnancies conceived after in vitro fertilization (IVF) versus intracytoplasmatic sperm injection (ICSI).Three-hundred thirty four women who had become pregnant after an IVF or ICSI procedure resulted in a total of 530 children referred between 2003 und 2009 to the Department of Obstetrics and Gynecology of the Medical University of Vienna, a tertiary care center, and were included in this retrospective cohort study. We assessed maternal and fetal parameters in both groups (IVF and ICSI). The main study outcomes were preterm delivery, the need for neonatal intensive care, and congenital malformations. Moreover, we compared the course of pregnancy between both groups and the occurrence of complications that led to maternal hospitalization during pregnancy.There were 80 children conceived via ICSI and 450 children conceived via IVF.Mean gestational age was significantly lower in the ICSI group (p = 0.001). After ICSI, the birth weight (p = 0.008) and the mean APGAR values after 1 minute and after 10 minutes were lower compared to that of the IVF group . Moreover, ICSI-conceived children had to be hospitalized more often at a neonatal intensive care unit (p = 0.004). There was no difference in pH of the umbilical artery or in major congenital malformations between the two groups. Pregnancy complications  and the need for maternal hospitalization during pregnancy were found significantly more often after IVF , compared to the ICSI group.When comparing IVF versus ICSI-conceived pregnancies at a tertiary care center, we found the course of pregnancy to be more complicated after IVF, whereas the primary fetal outcome seemed to be better in this group than after ICSI treatment. In many countries, there is a tendency for more and more women to delay childbearing until an age when their fertility begins to decline. Therefore, in vitro fertilization (IVF) procedures have become accepted as an alternative to natural conception, and pregnancies subsequent to assisted reproductive techniques (ART) are common in obstetrical departments.Although most pregnancies after IVF result in normal healthy outcomes, an increased risk for a number of obstetric and neonatal complications , compared to naturally conceived pregnancies, has been reported among singletons and twins -9. This While there are many studies that compare pregnancies after ART with spontaneously conceived pregnancies, fewer data are available that evaluate the differences between IVF and ICSI-conceived pregnancies. A recent study from Norway found that IVF pregnancies were associated with an increased risk of iatrogenic preterm delivery compared to ICSI pregnancies .The aim of the present study was to report systematically on the course of 334 IVF or ICSI-conceived pregnancies and to focus on the differences between both groups with regard to maternal and fetal outcome parameters.Between September 2003 and January 2009, 482 pregnant women with 722 fetuses, who had conceived via ART were referred to the Department of Obstetrics and Gynecology, Division of Obstetrics and Fetomaternal Medicine, Medical University of Vienna, Austria. Seventeen of the 722 fetuses were stillborn in the early gestational weeks, and, in 175 cases, there was insufficient information about the further course of pregnancy, and the status of birth and neonatal outcome, because patients were lost to follow-up. Therefore, after excluding cases of stillbirth and subjects lost to follow-up, a total of 334 pregnancies and 530 children could be included in our retrospective cohort study.Outcome variables included maternal parameters: i.e., age; BMI; gravity; number of fetuses; pregnancy complications such as pregnancy-induced hypertension, preeclampsia, premature rupture of membranes, cervical insufficiency, and premature uterine contractions; and number of hospitalizations; and fetal parameters: i.e., gestational age; birth weight; birth height; pH of the umbilical artery; APGAR after one minute; APGAR after 10 minutes; congenital malformation; admission of the newborn to a neonatal intensive care unit (NICU); and death of the infant.Institutional Review Board approval was obtained for the study, and women had given informed consent for the analysis of their data in the context of any retrospective evaluation. The present study was performed after approval of the responsible ethics committee. Ethikkommission der Universität Wien / Ethics commission of the Medical University of Vienna.Statistical analysis was performed by the Center for Medical Statistics, Informatics and Intelligent Systems, Section for Medical Statistics of the Medical University of Vienna.Descriptive results are given as mean ± standard deviation (or median and range) or frequencies and percentages. Spearman correlation coefficients were calculated.2-tests (Fisher’s exact tests). Comparisons between the two groups for fetal variables were performed using linear or generalized linear mixed models (ANOVA/ANCOVA).Comparisons between IVF and ICSI pregnancies for variables that were considered maternal parameters were performed using t-tests (Wilcoxon-tests) or chiIn addition, based on correlations and information from the literature, some of the models were adjusted for other known influence factors and, hence, are analyzed using linear or generalized linear regression models.As a secondary analysis, considering only singleton pregnancies, differences in gestational age between the two groups were calculated using the t-test (or Wilcoxon- test).Analyses were performed using SAS 9.2 and SPSS 20 software. P-values <0.05 were considered statistically significant.A total of 530 children of 334 mothers were included in our data analysis, 80 conceived via ICSI, and 450 via conventional IVF treatment.In 155 cases (21 ICSI/ 134 IVF), we found a singleton pregnancy, in 160 cases (25 ICSI/135 IVF) twins, in 17 cases triplets (3 ICSI/ 14 IVF), and in one case a quadruplet after conventional IVF treatment.The distribution between singleton and multiple pregnancies was not significantly different between IVF and ICSI.Maternal characteristics and outcome parameters are given in Tables Women with IVF showed statistically significantly more frequent pregnancy complications, such as premature rupture of membranes, premature uterine contractions, or cervix insufficiency (p = 0.0016), and had to be hospitalized more often during the second and third trimester of pregnancy (p = 0.0095).Neonatal outcome parameters are shown in Tables 2p = .019). Moreover, the gestational age was statistically significantly lower in the group of multiple gestations  compared to singletons, but also when comparing multiples after ICSI with multiples after IVF . Focusing only on singleton pregnancies, we found no significant difference in gestational age.Mean gestational age was significantly lower in the ICSI group when including all pregnancies , and moderately preterm from 28 to 34 weeks (age group 2), and compared the early age groups against children born after week 34 (age group 3). There was a statistically significant difference in distribution between ICSI with 7.9%, 46.05%, and 46.05% children, and IVF with 4.7%, 24.2%, and 85.5% children in the three age groups (p = 0.0039). Considering only singleton pregnancies, there were no children in the lowest age group, and 14.3% and 85.7% children in the higher groups after ICSI. In the IVF group, 0.8%, 8.1%, and 91.1% singletons were found in the three age groups. These distributions were not statistically significant (p = 0.62).2p = .016) when considering all fetuses; multiples had a lower birth weight compared to singletons in both groups, but there was no difference between IVF and ICSI-conceived pregnancies.Birth weight was statistically significantly lower within the ICSI group ; moreover, multiples had to be more often hospitalized compared to singletons ..High correlations, with correlation coefficients greater than 0.7, were found between the number of hospitalizations and premature rupture of membranes, gestational age and birth height, gestational age and birth weight, birth height and birth weight, APGAR1 and APGAR10, APGAR1 and infant death, and APGAR10 and infant death. Correlations between 0.4 and 0.7 could be found between gestational age and APGAR1, gestational age and APGAR10, gestational age and admission to the NICU, gestational age and infant death, birth height and APGAR1, birth height and APGAR10, birth height and admission to the NICU, birth height and infant death, birth weight and APGAR1, birth weight and APGAR10, birth weight and admission to the NICU, birth weight and infant death, number of fetuses and gestational age, and premature rupture of membranes and maternal hospitalization.The number of pregnancies after ART is still increasing and there is some data showing that IVF/ICSI is associated with a higher rate of complications with regard to both the course of pregnancy and neonatal outcome. Of note, the potential negative impact of micromanipulation techniques should be considered, but only a few research studies have made precise distinctions between IVF and ICSI pregnancies ,12,14.Therefore, we systematically analyzed and compared 334 pregnancies and 530 children after IVF and ICSI, and discovered that the course of pregnancy is more complicated in IVF pregnancies , whereas the primary fetal outcome  seems to be better in this group than after ICSI treatment.The significant association between IVF pregnancies and premature rupture of membranes, premature uterine contractions, and cervical insufficiency could be seen as concordant with the results of a smaller study that reported an increased preterm delivery risk in IVF versus ICSI-conceived pregnancies . Mean geThere were significant differences between the groups concerning gestational age, fetal birth weight, and mean APGAR levels, with lower levels for all variables in the ICSI group. Moreover, children in this group had to be admitted to the NICU more often.A plausible explanation for this phenomenon is lacking; one might, however, speculate that early manipulation of the egg cell for ICSI could have a long-term negative impact.When analyzing age groups, we found the risk of preterm delivery to be higher after ICSI treatment, but the fact that this observation no longer existed when focusing only on singleton pregnancies led to the conclusion that this might be predominantly due to multiple gestations within the ICSI group. Of note, the average gestational age in multiples was significantly lower in the ICSI group compared to the IVF group; this was not true of singleton pregnancies, as shown in Tables per se as a major risk factor for adverse perinatal outcomes after ART [Concerning major fetal malformations, there was no statistically significant difference between the two groups, which is in accordance with other studies ,16,17. Wfter ART . The facfter ART —possiblyA Chinese study analyzing birth defects in over 15400 children after ART found that the distribution of birth defects reflects the distribution in the general population, while the total frequency of birth defects was not significantly higher within the ICSI group, compared to insemination or conventional IVF .In our ICSI group, there was one case of a heart malformation and two cases of facial malformation, and, in the IVF group, two cases of heart malformation, one case of facial malformation, and one case of omphalocele combined with malformation of the limbs.Notably, the number of children after ICSI was unusually low (15%) in our collective. A possible explanation could be that all women whose data were analyzed in the present retrospective study were referred to our tertiary care center by their gynecologist for a distinct reason , and women who undergo an ICSI procedure, typically performed for male subfertility, might be younger and more healthy, and therefore, less often referred to a tertiary care unit. However, age, BMI, and pre-existing diseases, such as hypertension, did not differ between the two groups in our study.We have to admit, however, that the disproportionate underrepresentation of ICSI is an obvious limitation of our study.Moreover, the “origin” of sperm for ICSI  was unfortunately not systemically noted in our data. A recent cohort study revealed, however, that the above-mentioned methods of operative sperm collection seem to be as safe as conventional ICSI, IVF, and natural conception with regard to neonatal outcome, including congenital malformations .Another possible limitation of our study is the lack of an age-matched control group.We decided, however, against creating a control group from our high-risk collective at the University clinic (only a few uncomplicated pregnancies are treated at our center) in order to avoid comparing one high-risk collective , with another (St. p. ART) and preferred to use data concerning uncomplicated pregnancy outcomes from low-risk collectives reported in the literature.We systematically investigated a pre-defined group of Austrian women after conception via IVF/ICSI. We found that the course of pregnancies was more complicated after conventional IVF, whereas the primary fetal outcome seems to be better in this group, compared to ICSI treatment. Of course, our results must be interpreted with caution, as the study had a very skewed population, with underrepresentation of ICSI cases, and because the data were drawn exclusively from a tertiary care center. Further research that includes a larger cohort of ART pregnancies is required to confirm our hypothesis.ART: Assisted reproductive techniques; i.e.: Id est; ICSI: Intra cytoplasmatic sperm injection; IVF: In vitro fertilization.The authors declare that they have no competing interest.KN designed, analyzed, and reported the study. JO and DP analyzed the data. LS acquired the data presented in Tables


Assessment of risk factors for preterm birth in a population with high incidence of preterm birth and HIV infection.Secondary analysis of data for 2,149 women included in a community based randomized placebo controlled trial for the prevention of preterm birth  with gestational age at birth determined through ultrasound measurement in early pregnancy. Multivariate Logistic Regression analyses to obtain models for three outcome variables: all preterm, early preterm, and late preterm birth.No statistical differences were noted for the prevalence of HIV infection (p = 0.30) or syphilis (p = 0.12) between women who delivered preterm versus term. BMI (Adjusted OR 0.91 (0.85–0.97); p = 0.005) and weight gain (Adjusted OR 0.89 (0.82–0.97); p = 0.006) had an independent, protective effect. Previous preterm birth doubled the odds of preterm birth (Adjusted OR 2.13 (1.198–3.80); p = 0.01). Persistent malaria  increased the risk of late preterm birth (Adjusted OR 1.99 (1.05–3.79); p = 0.04). Age <20 (Adjusted OR 1.73 (1.03–2.90); p = 0.04) and anemia (Adjusted OR 1.95 (1.08–3.52); p = 0.03) were associated with early preterm birth (<34 weeks).Despite claims that HIV infection is an important cause of preterm birth in Africa, we found no evidence of an association in this population . Persistent malaria was associated with late preterm birth. Maternal undernourishment and anemia were independently associated with early preterm birth. The study did not assess whether the link was direct or whether a common precursor such as chronic infection was responsible for both maternal effects and early labour. Mortality in the first four weeks of life now accounts for 24–56% of all deaths among children under five and 75% of these occur in the first week of life. Of the estimated 4 million neonatal deaths each year, 99% occur in low income countries Globally, around 10–11% of all births, or an estimated 15 million births per year, are estimated to be preterm in vitro and in vivo experiments to link infection with preterm labour Although the reported rates of preterm birth are highest in sub-Saharan Africa and the highest absolute number of preterm births occurs in Asia, there are very limited data on factors associated with preterm birth in these populations. Preterm birth in these settings is presumed to be strongly associated with infective morbidity because burdens of infection are high in these countries, and because there is strong evidence from Given the burden of co-morbidities during pregnancy for many women living in resource poor settings, it is plausible that factors associated with preterm birth will differ from those in more affluent populations with better access to health care. The development of innovative solutions for prevention rely on a better understanding of cause A secondary analysis was performed using data collected as part of the APPLe trial .For the APPLe trial, pregnant women attending three rural and one peri-urban health centres in Southern Malawi were randomised to a placebo-controlled trial of oral azithromycin (1 g) given at 16–24 weeks and 28–32 weeks gestation. Gestational age was determined by ultrasound before week 24. Women and their infants were followed up until 6 weeks post delivery. The primary outcome was incidence of preterm delivery, defined as <37 weeks. Secondary outcomes were mean gestational age at delivery, perinatal mortality, birthweight, maternal malaria, and anemia. Analysis was by intention to treat Pregnant women <24 weeks gestation (ultrasound dated) were recruited at their first antenatal visit (booking visit) at which time they were screened for anemia (Hb<11.0 g/dl by battery operated HemoCue device), malaria  and syphilis (VDRL). All women who tested positive for syphilis were treated with benzyl penicillin (1 g i.m.). At the time the trial was conducted HIV testing was not mandatory and counseling and testing for HIV was available to all women who wished to be tested. Treatment to prevent maternal to child transmission was available at time of delivery as indicated.All women received iron tablets daily  with 0.25 mg folic acid and antimalarial prophylaxis (two doses of Fansidar: 500 mg sulphadoxine with 25 mg pyrimethamine). Women were seen at 4 weekly intervals until 32 weeks then 2 weekly until term. At 28–32 weeks, all women were reassessed for malaria and anemia and treated as needed. Women returned to the clinic for postnatal visits at 1 and 6 weeks. Community-based follow up was conducted for all women who failed to return to the antenatal or postnatal clinic as planned, or for women who withdrew from the study.For this secondary analysis, three groups of women were defined: those whose pregnancy resulted in an early or late preterm birth (gestation 24–36 weeks), and those who delivered at term (37–41 weeks). Women who delivered after 41 weeks (postterm) were not included in the analysis. Preterm birth was subdivided into early preterm (24–33 weeks) and late preterm birth (34–36 weeks). All women who delivered preterm started labour spontaneously. Data on the general demographics of the mother , outcome of previous pregnancy and information about the index delivery, including type of delivery, place and supervision of delivery was analyzed for each group. Women found to be anemic (Hb<11.0) or severely anemic (Hb<8.0) both at booking and during the second visit, were considered ‘persistently anemic’ or ‘persistently severely anemic’. Blood tests for malaria  were done both at the booking and second visit with women positive at both visits considered to have ‘persistent malaria’.HIV testing was performed retrospectively (2009) on stored blood samples (including booking blood sample and sample taken at 28–32 weeks gestation) using the Biorad GENSCREEN Ultra HIV Ag-AB kit for detection of HIV p24 antigen and antibodies to HIV1 and HIV 2.Data was analyzed using SPSS version 19. Frequencies, means and medians were used as appropriate to describe characteristics of all study participants. Women who gave birth to twins were excluded. Pearson's Chi Square was used to test for significant differences in dichotomous variables between women who delivered preterm versus term, while the Student's t-test was used to test differences for normally distributed continuous variables. The Mann Whitney U/Wilcoxon rank sum test was used to evaluate statistically significant differences among medians of variables with non-parametric distributions. This descriptive analysis was repeated for early and late preterm versus term birth. Multivariate Logistic Regression (MLR) analyses were conducted to obtain models for three outcome variables: all preterm, early preterm, and late preterm births.For multivariate analysis, all variables for which p<0.10 in the univariate analyses of the specific outcome variable were considered important and included in the starting model for the corresponding multivariate analyses. Using the backwards model selection method, each model was constructed to initially contain such variables and any that were clinically relevant. Goodness of Fit tests (Hosmer and Lemeshow) and deviance statistics were used to select the best multivariate model for each outcome. Odds Ratios and 95% Confidence Intervals (CI) were calculated for each variable that remained in the model. The level of statistical significance for all analyses was set at α = 0.05.Ethical approval was obtained from the College of Medicine Research Ethics Committee in Malawi. Informed signed consent was obtained from each participant after receiving a detailed explanation in the local language of the purpose of the study. In line with the Ethics Committee's instructions, HIV testing was performed retrospectively on stored blood samples only after the completion of the trial.A total of 2,297 women were recruited into the APPLe trial. Twenty-nine mothers who had twins were excluded from these analyses. For singleton pregnancies, data on gestation at birth was available for a total of 2,149 women. Of these 80.5% (1729/2149) delivered at term (37–41 weeks), 16.3% (351/2149) delivered preterm (<37 weeks), and 3.2% (69/2149) delivered postterm (>41 weeks gestation). Among women who delivered preterm, 75.2% (264/351) were late preterm births (34–36 weeks). Mean (SD) gestational age at birth was 38.6 (2.5) weeks. Figure 1General characteristics of the study population are given in Women who gave birth preterm were more likely to report a history of previous preterm birth  and previous neonatal death  compared to women who delivered at term. Compared to women who gave birth at term, a significantly greater proportion of women with preterm births were less than 20 years old  and had lower mean BMI .During pregnancy  women whCompared to women who delivered at term, a greater proportion of women with early preterm birth were underweight, with BMI <18.5 , and anemic during pregnancy .More women with early preterm birth reported a previous adverse pregnancy outcome including previous preterm delivery  and previous stillbirth . Other factors that were potentially important but of borderline statistical significance (0.05<p≤0.10) included the following: adolescence (age <20)  severe anemia . There were no other notable differences.Compared to women who delivered at term, women who delivered late preterm had significantly lower mean BMI at booking  , and gained less weight (kgs) between the booking visit and 28–32 week visit . Anemia  was more prevalent among women who delivered late preterm. Similarly, malaria at any time during pregnancy  and persistent malaria  were also more prevalent among women who delivered late preterm. Late preterm birth was also associated with a history of previous preterm delivery , and neonatal death .Association with age group approached statistical significance; age over 40 years was associated with increase in late preterm compared to term birth . Women over 40 were also more likely to report previous preterm birth (6.4% vs 4.1% p = 0.08) or a neonatal death .In this population, the prevalence of HIV was 26.2% overall  and was For all preterm birth, women with a history of a previous preterm delivery have more than twice the odds of having a repeat preterm birth .With increasing BMI the odds of preterm birth is significantly reduced  and this association is also seen with weight gain .Variables independently associated with early preterm birth were; age less than 20 years, anemia and a previous preterm birth. Adolescent age (age<20)  increased the odds of an early preterm delivery by more than 70%. Being anemic at any point during the pregnancy nearly doubled the odds of early preterm labour . Having had a previous preterm delivery increased the odds of an early preterm delivery by more than two and a half times .Factors that remained independently associated with late preterm birth were different to those for early preterm birth and included: BMI, weight gain and previous preterm birth. We found that an increased BMI  and weight gain  reduced the odds of late preterm birth. Similar to early preterm, a history of previous preterm birth  doubled the odds of late preterm birth.This study reports on the factors associated with preterm birth in an unselected rural pregnant population in Malawi, a country with the highest reported rate of preterm birth worldwide and with one in four women HIV positive. To the best of our knowledge, this is the first study from sub-Saharan Africa to report on the factors associated with preterm birth for a cohort of women in which gestational age has been reliably assessed with ultrasound.Although the incidence of preterm birth can be, as we have shown, very high in sub-Saharan Africa, there is very little data based on accurate gestational age assessment using prenatal ultrasound dating. The absence of relatively expensive ultrasound equipment is unsurprising in routine clinical assessment in low resource settings but ultrasound should be essential in future research studies of preterm birth The incidence of preterm birth in our population is almost identical to recently reported, ultrasound-dated figures from a clinical trial in Botswana – 16.7% It has been assumed that infective morbidity (including infection with HIV) is largely responsible for higher rates of preterm birth in Africa compared with other regions This is, therefore, a unique cohort of pregnant women with a high incidence of HIV positivity (26.2%), accurate ultrasound dating of gestational age, but no ARV treatment. In this cohort, we found no evidence that HIV status affects the risk of preterm birth. Such a study would not now be possible with the (very welcome) changes in this community of women having access to ARV treatment and therefore requesting HIV testing. Whilst there remains controversy as to whether ARVs (or certain classes of ARVs) increase the risk of preterm birth or not The implication is that, whatever other advantages stem from ARV use in HIV infected pregnant women in Malawi, there is no evidence from the study suggesting that reducing the risk of preterm birth is one.Some factors that we did find to be associated with preterm birth have been recognized in other populations. Thus, a history of previous preterm birth independently and significantly increased the odds of preterm birth overall ; late preterm birth  and early preterm birth .Similarly, persistent malaria was associated with a doubling of the risk of preterm birth.Although up to 30% of women had peripheral malaria parasitaemia at the time of booking, all women received presumptive treatment for malaria and persistent malaria was not common in this population (5%). However, if present, persistent parasitaemia was associated with increased odds for preterm birth. There has been discussion about the adequacy of sulphadoxine-pyrimethamine intermittent preventative treatment, given increasing parasitic resistance There was also an association with poor maternal nutritional state (low BMI and reduced weight gain) and, for early preterm birth, maternal anemia. We found that maternal weight played a significant role in the risk for all preterm birth, though differently for early versus late preterm. The odds of preterm birth were increased nearly three-fold for those who were underweight (BMI <18.5) at booking (even when controlled for HIV positive status), while the odds of late preterm were decreased if the patient gained weight (in between booking and the second visit) or increased her BMI, demonstrating a protective effect of weight against late preterm birth.Results obtained in our study are similar to those reported in a recent large systematic review and meta-analysis on maternal underweight that pooled data from 52 cohort studies and 26 case control studies mostly from developed countries and showed an increased risk of preterm birth in underweight women These findings raise the question of whether preterm birth can be prevented by improving maternal nutrition. A Cochrane review The mechanisms are unclear but both low BMI and anemia may have common cause in poor nutrition or chronic infection or both. Maternal anemia is recognized as an important risk factor for the mother, particularly if she has a postpartum haemorrhage. Our findings suggest that maternal anemia should also be recognized as a risk factor for preterm birth.All women who took part in this study attended for antenatal care on at least one occasion but the study did not include women who did not access care until after 24 weeks or who did not access antenatal care at all. However, in this setting, more than 90% of pregnant women do attend for antenatal care Because HIV testing was performed retrospectively on stored samples, CD4 counts were not obtained and no information was available about severity of HIV infection. Parasitic infection  was not assessed in this cohort. We have previously noted that hookworm and other parasites were uncommon in this population Preterm birth remains a significant risk factor for neonatal mortality. Developing a deeper understanding of the factors significantly associated with preterm birth in a community with an extremely high incidence and particularly identifying those factors that are modifiable, could help develop new approaches to antenatal (and pre pregnancy) care to prevent adverse pregnancy outcome. Our findings have underscored the importance of women's pregnancy history and identified maternal underweight, malaria and anemia as risk factors for preterm birth. Unexpectedly, we found no evidence that HIV status contributes to the risk of preterm birth.


Background: Cadmium (Cd) is an embryotoxic and teratogenic metal in a variety of animal species, but data from humans are limited.Objectives: The aim of the present study was to assess the effects of maternal Cd exposure in pregnancy on size at birth.n = 1,616). Urinary Cd was measured with inductively coupled plasma mass spectrometry and adjusted for specific gravity.Methods: This prospective cohort study was nested in a population-based nutritional supplementation trial in pregnancy conducted in rural Bangladesh. We selected women recruited from February 2002 through January 2003 who had a singleton birth with measurements of size at birth and had donated a urine sample in early pregnancy for Cd analyses  was significantly negatively associated with birth weight  and head circumference . However, associations appeared to be limited to girls, with little evidence of effects in boys. A 1-μg/L increase in Cd in maternal urine was associated with a 0.26-cm  and 0.24-cm  decrease in girls’ head and chest circumferences, respectively, and a 45-g  decrease in birth weight. Quantile regression analyses indicated that associations with maternal Cd were similar for girls of smaller (25th percentile) and larger (50th and 75th percentiles) sizes at birth.Conclusion: We found evidence of a sex difference in the association between maternal Cd exposure and birth size, which was apparent only in girls. Results add support for the need to reduce Cd pollution to improve public health. Human exposure to the toxic metal cadmium (Cd) occurs mainly through food, such as cereals, seafood, and offal, and inhalation of tobacco smoke . Once abThere is, however, little information on the effects of Cd exposure in early life. Cd has been shown to be both embryotoxic and teratogenic in a variety of animal species , but thiIn the present study, we took advantage of our large, population-based, longitudinal mother–child cohort in Bangladesh to assess the effects of maternal Cd exposure on size at birth. We previously reported that arsenic (As) exposure is associated with reduced size at birth . AdditioStudy area and design. The present study was nested in a population-based food and micronutrient supplementation trial in pregnancy in women in rural Bangladesh , which enrolled approximately 4,500 pregnant women from November 2001 through October 2003, as described previously , as well as the regional ethics committee at Karolinska Institutet, Sweden. Oral and written consents were obtained from the women.Exposure assessment. Of the 1,697 women, 1,616 donated a urine sample, on average at gestational week 8, and this urine sample was used for assessment of Cd exposure. Urinary Cd is a well-documented biomarker of chronic exposure (n = 81). However, those who donated a sample had slightly longer gestation  than those who did not .exposure . These 1111Cd was monitored. The sample preparation and analytical methods have been described elsewhere . The obtained mean (± SD) urinary Cd concentrations in the two control materials were 0.26 ± 0.05 μg/L  and 4.8 ± 0.14 μg/L (5.06 ± 0.22), respectively. We have previously measured the sum of inorganic As and its methylated metabolites, referred to as urinary As, in these women because many are highly exposed to As via drinking water  at Karolinska Institutet . Samples were stored at –70°C in acid-washed plastic vials. The ICPMS was operated in helium mode and lsewhere , 2009. Nng water . These mng water . To compng water .Outcomes and covariates. Birth weight was measured with electronic or beam scales with precision of 10 g , length with a locally produced wooden length board (accurate to 1 mm), and head and chest circumference with a flexible nonstretchable measuring tape (accurate to 1 mm) (n = 26), we used the last menstrual period estimated by ultrasound measurements (to 1 mm) . Approxito 1 mm) . Gestatiurements .Covariate information was obtained during household visits by the health research workers and at routine visits at the health facilities, as well as from the Health and Demographic Surveillance System database maintained by ICDDR,B . Maternal height and weight were recorded at the health facilities, approximately in gestational week 8. Education was defined as years of formal schooling and categorized as no education, < 5 years, ≥ 5 to < 10 years, and ≥ 10 years. SES was classified according to a wealth index based mainly on household assets, as described previously . MaternaStatistical analyses. The statistical analyses were performed with Statistica for Windows  and STATA . All tests were two sided, and a p < 0.05 was considered statistically significant. Bivariate analyses between exposures, sizes at birth, and covariates were evaluated by Spearman’s correlation coefficient or analysis of variance depending on the type of data analyzed. The p-value for the difference between two independent groups was determined with the Mann–Whitney U-test.p < 0.05) in the bivariate analyses or that had previously been associated with size at birth. Maternal age and parity, and maternal education and SES were highly correlated (rs > 0.50). Therefore, we adjusted for maternal age and SES only, because they were more strongly associated with outcomes than were parity and maternal education. We evaluated colinearity by tolerance and variance inflation factor in the linear regression analyses. The final multiple linear regression analyses were adjusted for maternal age, BMI, SES, hemoglobin in gestational week 14, urinary As at gestational week 8, betel use, season of birth, gestational age at birth, and sex. Additionally, we stratified by sex and by SES (median split) and repeated the above analysis. Also, we assessed whether adding the different food  and/or micronutrient supplementations (three different types) into the models modified the association between Cd and size at birth. We used “seemingly unrelated estimation” in STATA to adjust for conducting multiple tests on a set of correlated outcomes dealing with size at birth and compared these model estimates with estimates from the analysis described above.We further assessed associations between maternal urinary Cd (nontransformed) and size at birth  using multivariable-adjusted linear regression analyses. The residual analyses indicated no major deviation from the assumptions of linear regression. We adjusted for variables significantly associated with either size at birth or urinary Cd  of the response variable. Thus, quantile regression allows us to estimate associations between an exposure and the outcome at different levels of the outcome distribution, instead of associations with the mean value of the outcome only, and thus provides a method to determine whether a predictor variable, such as Cd, may have a different association with birth size among children with low birth size compared with children with normal birth size . Additio2. None of the women reported smoking during pregnancy, but approximately 38% reported betel chewing. About one-third of the women were primiparous, and the multiparous women had on average two children . The background characteristics and biomarkers of the mothers are presented in In the bivariate analyses, maternal urinary Cd was not significantly correlated with birth weight, length, and head or chest circumference but was positively correlated with maternal age and urinary As concentrations and negatively correlated with maternal education, SES, and hemoglobin . In addip = 0.77). Multiparous women had significantly higher urinary Cd concentrations  than did primiparous women , but they were also older than the primiparous women . Betel chewing was not significantly associated with maternal urinary Cd or any of the birth outcomes (data not shown).Urinary Cd did not differ between mothers of infants born preterm  and those born at term , birth weight , and birth length . In boys, urinary Cd was positively associated with birth length  and birth weight  and weakly associated with reduced chest circumference . Head circumference was not correlated with maternal urinary Cd in girls or boys In girls, urinary Cd was negatively associated with chest circumference . Moreover, maternal urinary Cd was close to negatively associated with mean chest circumference , whereas no association was found with birth length. Sex was significant in all models, confirming that, on average, girls were smaller than boys . When a multiplicative interaction term between urinary Cd and sex was included in the multivariable-adjusted regression analyses (p > 0.05). The stratified analyses showed that the inverse associations between maternal urinary Cd and mean birth outcomes were evident only in girls . Adding the different food and micronutrient supplementations that were ingested during pregnancy into the models did not modify the associations between Cd and size at birth (data not shown), even when the analysis was restricted to the girls.The multivariable-adjusted quantile regression analysis confirmed that maternal urinary Cd was associated with birth size in girls but not in boys . MoreoveThe present study, which to our knowledge is the largest to estimate effects of Cd on fetal development, shows an unexpected difference in the association between maternal Cd exposure during pregnancy and infant size at birth by sex, with inverse associations in girls but little evidence of an effect in boys. The strongest associations were found for head circumference and birth weight. A 1-μg/L increase in Cd in maternal urine during pregnancy was associated with a decrease in head circumference of 0.26 cm and in birth weight of 45 g in girls. The magnitude of the estimated effects is not necessarily of clinical importance for individual children but may have considerable public health relevance given the high prevalence of elevated exposure to Cd, mainly through the diet.The main strengths of this study include the prospective study design and the large sample size with a wide range of Cd exposure. Also, we had extensive data on potential confounders, including maternal age, nutrition, season of birth, and SES. We also adjusted for As exposure and betel chewing, which have previously been associated with size at birth . HoweverWe tested the robustness of our findings using both conventional multivariate linear regression models and quantile regression models. The quantile regression estimates for the median generally agreed with the linear regression estimates in terms of direction and magnitude, indicating that the linear regression estimates were not unduly influenced by outlying values. We did not find any evidence that Cd differentially affected children of smaller size.A limitation of the study is that we did not measure Cd in cord blood, which might have provided more precise information of the prenatal Cd exposure. Two previous studies, although limited in size (49 and 45 women), found inverse associations between cord blood Cd concentrations and birth weight . Anotherin vitro and in women with increased Cd exposure via smoking  markedly reduced 11β-HSD2 gene activity, mRNA, and protein levels in cultured human trophoblastic cells in vitro  axis and thereby reduce fetal growth in a sex-specific manner. Rats given drinking water with 50 mg Cd/L had lower concentrations of IGF-1 and insulin-like growth factor-binding protein 3 (IGFBP-3) than did controls . In humade novo DNA methylation, which is essential for normal embryogenesis  was higher than that reported in young women in the United States  and Europe  , probablWe found significant inverse associations between maternal Cd exposure and birth anthropometry in girls, especially head circumference and birth weight, but no associations in boys. These findings, along with evidence from previous experimental and observational studies, suggest that there may be sex differences in both toxicokinetics  and toxicodynamics of Cd. It is essential to follow the children through childhood to clarify whether the apparent effect on growth remains and whether the early-life Cd exposure is associated with other health outcomes later in childhood. This study clearly emphasizes the need to consider early-life effects of Cd in health risk assessments and to reduce Cd pollution worldwide.


We investigated pathways linking offspring birth weight to maternal diabetes risk in later life by taking into account a range of prospective early-life and adult maternal factors.1c) at age 53 years in 581 mothers who had a first birth between age 19 and 25 years, and had data on potential confounders or mediators.In a national birth cohort study, we examined the relationship between offspring birth weight and maternal glycated haemoglobin  −3.5, −0.1; P = 0.03]. This relationship was mostly accounted for by gestational age that was inversely related to maternal HbA1c . Other risk factors for high HbA1c were smoking and high BMI at 53 years. There was a significant interaction between offspring birth weight and maternal childhood social class (P = 0.01). Mothers from a manual background with higher birth weight offspring had lower HbA1c ; this was not observed for mothers from a non-manual background .Mean age at first birth was 21.5 years. After adjustment for maternal body mass index (BMI), mean percentage change in maternal HbAShort gestational age and low offspring birth weight may be part of a pathway linking impaired early maternal growth to diabetes risk in later life. A second possible pathway linking higher offspring birth weight to later maternal glucose status was also identified. These potential pathways require further investigation in cohorts with a wider maternal age range so that the early targeting of public health initiatives can be assessed.Diabet. Med. 25, 530–535 (2008) Reproductive function, in terms of menstrual patterns, age at first pregnancy, parity and pregnancy outcome, is not only integral to women's overall health and wellbeing from menarche to menopause, but is increasingly recognized as a sentinel of chronic disease in later life .With regard to pregnancy outcomes, a series of studies has shown that mothers of smaller babies tend to live shorter lives, and are more likely to die from cardiovascular disease , 3. TheyThe associations between lower offspring birth weight and increased risk of maternal diabetes and cardiovascular disease do not appear to be explained by adult maternal characteristics, such as smoking or socioeconomic disadvantage, which could both lower the birth weight of offspring and increase chronic disease risk. Nor do these associations appear to be due to shorter gestational age or other pregnancy complications that may result in a baby of lower birth weight, although in one study offspring gestational age accounted for some of the inverse relationship between offspring birth weight and maternal diabetes mortality . The inv1c) at age 53 years and the birth weight of first-born offspring in mothers participating in the Medical Research Council (MRC) National Survey of Health and Development, a prospective UK birth cohort study. HbA1c corresponds to mean plasma glucose concentrations and high HbA1c affects diabetes risk in people without diabetes [1c.We examined the relationship between glycated haemoglobin . Height and weight were used to calculate body mass index (BMI). Information on current or most recent occupation was used to derive adult social class, based on the British Registrar General's standard classification, categorized as non-manual  and manual . Parity was based on reported live births.As part of the home visit at age 53 years, trained research nurses measured height and weight and took a non-fasting venous blood sample according to standardized protocols , and int1c, self-reported height and weight at 20 years were used to derive a measure of BMI (kg/m2) that was closest to the women's pre-pregnancy BMI.Own birth weight, recorded to the nearest quarter pound, was extracted from birth records within a few weeks of delivery in March 1946 and converted into kilograms. Childhood social class was based on information on father's occupation collected prospectively in childhood from the mother. In order to investigate if weight change since early adult life could provide a possible explanation for the association between offspring birth weight and maternal HBA1c at 53 years and complete data on offspring birth weight and gestational age, own birth weight, current BMI, height, smoking, parity, and child and adult social class. In this sample, diabetes was diagnosed in 16 women, with its onset occurring at a mean age of 39 years. There were no cases of childhood diabetes. In 13 cases the onset of diabetes had occurred after the first birth and in the remaining cases around the same time as the birth. The geometric mean HbA1c was 5.64%, mean BMI was 27.5 kg/m2, 29% were smokers, 66% were from the manual social class in childhood and 35% were in the manual social class in adulthood. The 581 mothers with complete data had similar offspring birth weight and gestational age to the 415 with incomplete data. Those excluded had significantly higher mean BMI than those included. There were no differences in HbA1c or any of the other possible confounding or mediating variables. Mean age at first birth was 21.5 years.Analysis was done in the 581 women with measures of HbA1c and diabetes at age 53 years and to potential confounders or mediators.The difference in average offspring birth weight between the sexes was accounted for by subtracting 116 g from the male offspring birth weight . Offspri1c for the 16 women with diabetes was 7.3%, and only six had values within the normal range (< 6.1%). As the real outcome of interest is the untreated HbA1c, we used a censored normal regression  to examine the relationship between offspring birth weight and maternal HbA1c. In this way the observed values of the diabetic women were censored, so that the actual unobserved values were assumed to be at least that value or higher. The natural logarithm of HbA1c (×100) was used to reduce the right skewness of the distribution. Therefore the regression coefficients in these models can be interpreted as symmetric percentage change in HbA1c[The mean HbA in HbA1c.1c for maternal BMI at 53 years. Possible confounding or mediating factors, namely offspring gestational age, maternal birth weight, height, smoking, parity, and child and adult social class were then added in turn. To test whether change in BMI between 20 and 53 years of age affected the relationship between offspring birth weight and maternal HbA1c, we substituted BMI at age 53 with BMI change. To test whether an effect of offspring birth weight on maternal HbA1c was restricted to women who had a shorter pregnancy, we included an interaction term  in a model with the two main effects and maternal BMI at 53 years. Similarly, we included interaction terms in models with birth weight and childhood or adult social class to test whether an effect of offspring birth weight on maternal HbA1c was modified by social circumstances in childhood or adult life. This was done because evidence from other studies has suggested that associations between early growth and later cardiovascular risk are stronger for those from poorer childhood or adult circumstances than for those in better circumstances [This model was used to adjust the relationship between offspring birth weight and maternal HbAmstances , 17. All1c at age 53 years decreased by −1.52%  per kg change in birth weight  per kg change in birth weight (P = 0.03) (1c was similar (not shown). Gestational age was strongly associated with birth weight  for each additional week of gestation. The percentage difference in maternal HbA1c for a kg change in birth weight was considerably reduced after adjusting for gestational age .Maternal HbAh weight . After a = 0.03) . The effh weight  and inveonal age . There w1c  and percent change for those from a non-manual background was 1.87% . There was no evidence of an interaction between offspring birth weight and adult social class . Maternal parity was not associated with the birth weight of first-born offspring , smoking (P = 0.002) and shorter gestational age in first-born offspring (P = 0.01). The P-value for the interaction term between childhood social class and offspring birth weight remained significant (P = 0.02) when added to the final model.The final model showed no effect of offspring birth weight on maternal HbA factors . The mos1c in late middle age. Compared with previous studies that have found an inverse relationship between offspring birth weight and diabetes risk [1c. A recent Swedish record linkage study also found an inverse association between gestational age and maternal diabetes mortality and that the effect of gestational age reduced the association between offspring birth weight and maternal diabetes mortality [In this cohort of mothers who had a first birth between 19 and 25 years of age, gestational age rather than low birth weight was associated with higher maternal HbAtes risk –6, 18, otes risk , 6, 18. ortality , cerebroortality  and riskortality , 22. In ortality . It is kortality . This coortality , that leortality .1c at age 53 years.Unlike previous studies, we were able to investigate the role of change in BMI during adult life. We found no evidence for the suggestion  that fas1c. This interaction needs to be interpreted with caution and may be a chance finding and thus requires replication in other studies. However, it may be that the risks associated with gestational diabetes/glucose intolerance during pregnancy (resulting in a bigger baby at birth) and diabetes/glucose intolerance in later life is more important for women from a non-manual social class than for those from a manual social class, whereas the factors linking lighter babies with increased maternal glucose intolerance may predominate in women from a manual social class [In women from a non-manual childhood social class, those who had higher birth weight offspring had higher HbAal class , 26, 27.1c. Within this group of young mothers, adjusting for parity had little effect on the relationship between offspring birth weight and maternal HbA1c. Another limitation of this study is the lack of data on father's offspring, which would have provided an opportunity to unravel differences between the paternal and maternal influences on offspring birth weight and diabetes risk.This study was limited to mothers who had a first birth between 19 and 25 years of age. Women who had their first born before age 25 years had higher parity, and this may have increased their diabetes risk compared with women whose first child was born later. This could limit the generalizability of our findings. In our recent research  we found1c in late middle age, taking into account a broad range of maternal factors across the life course. The results show that gestational age rather than low birth weight was associated with higher maternal HbA1c, and this may be part of a pathway linking impaired early maternal growth to diabetes risk in later life. A second possible pathway linking higher offspring birth weight to later diabetes risk in women from a non-manual social class was also identified. The relative importance of these two pathways needs to be investigated in older and younger birth cohorts and in samples with a wider maternal age range. Research should also focus on the underlying genetic and environmental mechanisms that determine the pathways and assess the potential role for early targeting of public health initiatives.In conclusion, this study has used prospective data to investigate the link between offspring birth weight and maternal HbA