Endogenous signaling molecules derived from lipids, peptides, and DNA, are important regulators of physiological processes during pregnancy. The effect of their collective impact on preterm birth (delivery < 37 weeks gestation) is understudied. We aimed to characterize the associations and predictive capacity of an extensive panel of eicosanoids, immune biomarkers, oxidative stress markers, and growth factors towards preterm birth and its subtypes. We conducted a cross-sectional study of pregnant women (recruited < 15 weeks gestation) in the LIFECODES birth cohort, which included 58 cases of preterm birth and 115 controls that delivered term. Among the cases there were 31 cases who had a spontaneous preterm birth (cases who had spontaneous preterm labor and/or preterm premature rupture of membranes) and 25 that had preterm birth associated with aberrant placentation (cases who had preeclampsia and/or intrauterine growth restriction) and 2 cases that could not be sufficiently categorized as either. We analyzed single biomarker associations with each preterm birth outcome using multiple logistic regression. Adaptive elastic-net was implemented to perform a penalized multiple logistic regression on all biomarkers simultaneously to identify the most predictive biomarkers. We then organized biomarkers into biological groups and by enzymatic pathways and applied adaptive elastic-net and random forest to evaluate the accuracy of each group for predicting preterm birth cases. The majority of associations we observed were for spontaneous preterm birth, and adaptive elastic-net identified 5-oxoeicosatetraenoic acid, resolvin D1, 5,6-epoxy-eicsatrienoic acid, and 15-deoxy-12,14-prostaglandin J2 as most predictive. Overall, lipid biomarkers performed the best at separating cases from controls compared to other biomarker categories . Among the enzymatic pathways that differentiate eicosanoid metabolites, we observed the highest prediction of overall preterm birth by lipoxygenase metabolites using random forest , followed by cytochrome p450 metabolites using adaptive elastic-net . In this study we translate biological hypothesis into the language of modern machine learning. Many lipid biomarkers were highly associated with overall and spontaneous preterm birth. Among eicosanoids, lipoxygenase and cytochrome p450 products performed best in identifying overall and spontaneous preterm birth. The combination of lipid biomarkers may have good utility in clinical settings to predict preterm birth. Babies who are born preterm have increased risk for health conditions later in life, including neurodevelopmental and sensory disorders, physical disabilities, cardiovascular disease, and impaired respiratory function4. Live births are broadly classified as preterm if they occurred at less than 37 weeks gestation, and there is great heterogeneity in clinical presentation and other circumstances contributing to preterm birth. Therefore, differentiation of preterm birth cases by clinical subtypes provides greater insight on the underlying antecedent mechanisms of preterm delivery. For example, spontaneous preterm births can involve spontaneous preterm labor or premature rupture of membranes, which is determined by the presence of vaginal pooling and either documentation of nitrazine-positive testing or ferning followed by regular uterine activity5. Whereas preterm birth associated with aberrant placentation is dominated by the presentation of preeclampsia (encompassing onset of hypertension and proteinuria) or intrauterine growth restriction5.Preterm birth is a significant public health issue that occurs in approximately 10% of live births in the U.S., and remains the leading cause of neonatal mortality6. Furthermore, several biomarkers of oxidative stress and inflammation serve as signaling molecules that are integral for not only regulating maternal hormones but also facilitating cross talk between the maternal circulation and fetal compartment8.During pregnancy, systemic oxidative stress – the imbalance of reactive oxygen species and antioxidant molecules – can lead to inflammation and perturbation of several physiological processes that are integral for the progression of a healthy pregnancy. For example, oxidative stress and inflammation can cause tissue damage and alter vascularization, both of which can be harmful during critical stages of pregnancy, such as placentation, quiescence, cervical ripening, and induction of labor10. For inflammation, this included the general marker C-reactive protein (CRP) as well as a panel of cytokines; for oxidative stress, this included 8-isoprostane, a marker of lipid peroxidation, and 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage. These represent only a small fraction of the repertoire of signaling molecules that regulate inflammation during pregnancy. Nonetheless, we learned that the pro-inflammatory cytokine interleukin-6 was associated with increased risk for spontaneous preterm birth, while the anti-inflammatory cytokine interleukin-10 was elevated among cases of preterm birth associated with aberrant placentation9. Among oxidative stress markers, we found that overall and spontaneous preterm birth were positively associated with 8-isoprostane and inversely associated with 8-hydroxydeoxyguanosine10.We have previously reported associations between preterm birth and select biomarkers of inflammation and oxidative stress11. Eicosanoids are intimately connected to immunological signaling molecules and inflammation, and are therefore potent regulators of physiological processes11. Animal studies also indicate overlapping consequences clustered by enzyme specific metabolites. For example, metabolites produced through LOX pathways resulted in inflammation, vascular remodeling, and altered renal function12. Furthermore, although many eicosanoids, such as prostaglandins, can cause pro-inflammatory stimulation of target tissues, some groups of eicosanoids such as resolvins can be anti-inflammatory and resolve inflammation14. Altogether, the effects of eicosanoids on inflammation and cardiovascular activity provide a mechanistic link for preterm birth15.We sought to expand our panel of biomarkers to investigate the combined effects of those previously measured biomarkers in addition to a newly measured panel of eicosanoids – a large class of lipid metabolites. Eicosanoids are metabolized from large fatty acids such as arachidonic acid and linoleic acid and produced through many enzymatic pathways, including three broad families of enzymes: lipoxygenases (LOX), cytochrome P450 (CYP450), and cyclooxygenases (COX)Our primary study aim was to evaluate a group of 65 biomarkers in association with preterm birth and its subtypes. By measuring a large panel of eicosanoids and other biomarkers of inflammation and oxidative stress, we obtain greater coverage of signaling molecules, which could potentially increase the capacity to predict preterm birth. However, there are also major challenges that arise from analyzing high dimensional data, including multicollinearity and the risk for false discoveries due to multiple testing. We integrated variable selection and machine learning methods to circumvent some of the challenges with high-dimensional data. Our secondary study aim was to focus more deeply on the biological context of observed associations by grouping our analyses based on categories of molecules, and then by enzymatic pathways within the eicosanoids panel. We hypothesized that the combination of biomarkers would predict preterm birth, and that select pathways among eicosanoids will have differential predictive capacity. We translated this hypothesis by using a grouped variable selection framework.The demographic characteristics of the subjects in this study are summarized in Table Figures Combined with the biomarkers that were associated with overall preterm birth, we observed fourteen additional lipid biomarkers associated with increased risk for spontaneous preterm birth Fig. . These bWe observed moderate to strong correlations between biomarkers Fig. . Correlaλ increased for all preterm birth , and lipid damage markers and protein damage markers exited the model last (indicating greatest importance) as the penalty on the coefficients increased Fig. . For sporth Fig. ; CYP450 rth Fig. . The groThe computed area under the Receiver Operating Characteristic (ROC) curve (AUC) is a measure of discrimination, where in our study an AUC value of 0.5 would indicate that a given combination of biomarkers has no better accuracy to predict preterm birth than chance, while an AUC value of 1 represents perfect accuracy at predicting preterm birth. While AUC values above 0.9 typically represent diagnostic tests of biomarker combinations with the greatest utility in separating cases from controls, tests with AUC values between 0.7–0.9 indicate biomarker combinations that have fair to good utility and can potentially be improved with a larger training data set or expanded measurement of additional predictive biomarkers. We reported AUC values corresponding to prediction of all preterm birth Table  and sponAccording to Table When spontaneous preterm birth was considered, the group of lipid markers again gave the largest AUC  and sensitivity  among the five major groups for each training method Table . The adaIn this study, we made two primary contributions: (1) integrated cutting edge machine learning methods and multiple inferential tools  to analyze an extensive panel of biomarkers related to inflammation, oxidative stress, and angiogenesis, in association with preterm birth and its subtypes; and (2) contextualized associations with preterm birth by grouped analyses of biomarker categories and enzymatic pathway groups for eicosanoids. To our knowledge, this is the first study to investigate eicosanoids and associated biomarkers to this degree of metabolite coverage during pregnancy in association with overall preterm birth and its subtypes. Several biomarkers were associated with overall preterm birth in single biomarker models, and adaptive elastic-net identified five biomarkers -EET, and 15DO12,14-PGJ2) to be most predictive of overall preterm birth. The overall preterm birth outcome contains multiple constituent sub-pathologies, therefore interpretation of these associations is more crude compared to focusing on preterm birth subtypes. Once we disaggregated cases by preterm birth subtypes, we learned that many of the effect estimates were largely driven by spontaneous preterm birth, where adaptive elastic-net identified four biomarkers -EET, and 15DO12,14-PGJ2) to be most predictive. Whereas for preterm birth associated with aberrant placentation, adaptive elastic-net identified two biomarkers with protective associations (PGF and LTB4). Prediction of preterm birth was most accurate with the lipid biomarkers using both adaptive elastic-net and random forest. When focusing solely on the lipid biomarkers, adaptive elastic-net showed greater accuracy in preterm birth prediction among metabolites of the CYP450 pathway, while random forest reported metabolites of the LOX pathway to be more accurate. Overall, these findings provide insight on prioritization of biomarker groups for the prediction of preterm birth, and future studies should explore CYP450 and LOX metabolites to validate these findings.17. The impact that 5-oxoETE has on target sites can vary by cell type, but broadly involve intracellular changes that lead to heightened chemotaxis – an integral process that attracts immune cells to target tissues to drive the inflammatory process18. 5(6)-EET is a fatty acid metabolite of AA produced through the CYP450 pathway and commonly originates from the liver, kidneys, and vascular endothelium19. Importantly, 5(6)-EET is a modulator of cardiovascular function and predominantly acts as an anti-inflammatory vasodilator20. We observed protective associations between 5(6)-EET and spontaneous preterm birth, which aligns with the predominant paradigm of an anti-inflammatory and anti-hypertensive profile. However, other studies have observed higher plasma and placental concentrations of 5(6)-EET or total EET in women with preeclampsia compared to normotensive women21 and non-pregnant women22. Another study found lower concentrations of 5(6)-EET in amnion of women with preeclampsia compared to laboring women that had a cesarean section23. Differences between studies underline potential nuances to 5(6)-EET activity, potentially masked by our uncertainty of concentrations at target tissues at the maternal-fetal interface.The biomarkers that adaptive elastic-net identified as most predictive for spontaneous preterm birth are all eicosanoid metabolites, with each of the three enzymatic pathways and parent compounds being represented. 5-oxoETE is a polyunsaturated fatty acid product derived from AA processing via the LOX pathway. Receptors for 5-oxoETE are highly expressed in peripheral leukocytes, lungs, kidney, liver, spleen, and placenta24. Although we observed positive associations between 15DO12,14-PGJ2 and spontaneous preterm birth, several pro-inflammatory prostaglandins  were also positively associated with spontaneous preterm birth. 15DO12,14-PGJ2 may likely be up-regulated during inflammation to help with the resolution of inflammation, thereby partly explaining why we observed positive associations with spontaneous preterm birth. A similar conclusion may be drawn from the positive association we observed between spontaneous preterm birth and the anti-inflammatory molecule RVD1, which belongs to the group of compounds called resolvins and is a LOX pathway product of DHA25. Interestingly, our findings suggest that both pro- and anti-inflammatory fatty acid metabolites are associated with increased risk for overall and spontaneous preterm birth, emphasizing the utility of evaluating these biomarkers collectively as a combination of predictors to enhance the classification of preterm birth cases early in pregnancy.The prostaglandin 15DO12,14-PGJ2 has been shown to elicit anti-inflammatory properties through inhibition of the nuclear transcription factor NFκ-B26. Previous studies observed lower levels of PGF among women with preeclampsia – one requisite for preterm birth associated with aberrant placentation – indicating that higher concentrations of PGF may potentially be protective of this type of preterm birth26. LTB4 is a leukotriene metabolized from AA through the LOX pathway, and has pro-inflammatory properties through stimulating vasoconstriction, platelet aggregation, and cellular migration of immune cells27. Although LTB4 has been previously reported to increase the risk for preeclampsia27, we observed a protective relationship between LTB4 and preterm birth associated with aberrant placentation. One possible explanation is that LTB4 elevation may potentially be a proxy for increased anti-inflammatory biomarkers, given evidence that LTB4 concentrations can remain high before and after onset of preeclampsia27. Conversely, this observation, alongside numerous null associations, may be due to underpowered sample size of this type of preterm birth in our study.Among the predictors that were linked to preterm birth associated with aberrant placentation, adaptive elastic net identified PGF and LTB4 as most predictive, both of which are protective for this type of preterm birth. PGF is a growth factor that promotes angiogenesis in part by stimulating cellular migration and recruitmentcases = 37, ncontrols = 37) observed higher concentrations of AA in plasma collected at delivery from women who delivered preterm compared to AA in plasma collected at 34 weeks gestation from women that delivered term, which is consistent with the increased risk we observed between AA and spontaneous preterm birth28. Another study evaluated differences in PGF2α and PGE2 by preterm status  and found lower levels of both in placenta and amnion samples from cases collected at delivery, but did not find significant differences in maternal plasma29. A separate case-control study  found lower levels of PGF2α measured in serum collected at the onset of active labor in preterm birth cases compared to controls30. However, another case-control study of preterm birth  did not observe notable differences in urinary concentrations of PGF2α31. Although we did not measure PGF2α, we did find higher concentrations of its metabolite 13,14DHK-PFG2α among spontaneous preterm birth cases. Ultimately there are few existing studies for comparisons, however our findings are largely consistent with current frameworks for biological mechanisms of eicosanoids.Very few studies have investigated circulating maternal eicosanoids and lipid biomarkers in association with preterm birth. One case control study of preterm birth  observed high intra-individual variability in two repeated measurements of blood eicosanoids38. In the LIFECODES cohort, we have also leveraged repeated measurements of the inflammatory biomarkers (CRP and cytokines), and observed moderate intra-individual variability9. These results provide preliminary evidence that although single time point measurements may have good utility in some study samples, repeated measurements would be advantageous when intra-individual variability is moderate or high. Future studies should consider measuring these biomarkers at multiple study visits that range across each trimester of pregnancy and conduct longitudinal analyses to determine if specific periods of gestation have greater predictive capacity.This study contains several limitations that should be discussed to improve future studies. First, our study had low numbers of cases, especially as we disaggregated to preterm birth subtypes. We may have been underpowered to observe smaller effect estimates with some of the biomarkers that we measured. The greater count of spontaneous preterm birth cases compared to preterm birth associated with aberrant placentation may have biased the results of overall preterm birth towards the biological mechanisms underlying spontaneous preterm birth. Additionally, samples were collected between 2006 and 2008, therefore biomarkers in our samples may be susceptible to degradation over long periods of storage. However, rigorous storage protocols for freezing and preserving samples partially ameliorate this problem. Furthermore, the measurement error bias associated with long storage periods would likely lead to attenuation of research findings towards null, rather than create false positives. Another limitation in our study was the cross-sectional study design and we were limited to a single time point measurement of biomarkers, therefore we were unable to evaluate time-course concentrations of individual biomarkers during pregnancy. One previous repeated measures study of select eicosanoids in adult women (n = 9) observed low intra-individual variability across eight repeated blood measurementsSince we conducted multiple comparisons, some of the single biomarker models may be at risk for false discoveries. However, the biomarkers that we discussed in depth that were selected by adaptive elastic-net circumvent the drawbacks of multiple comparisons since it evaluates all biomarkers in a single predictor matrix simultaneously rather than conducting multiple tests. We are also limited by the fact that we measured for circulating plasma or urinary biomarkers, which provides limited insight on the physiology occurring locally at the maternal-fetal interface and other target tissues. It is critical that future studies consider measuring endogenous biomarkers in multiple biological media across various time points in pregnancy. Among the biomarkers that we measured, our study focused predominantly on biomarkers measured in plasma samples. Other less invasive media such as urine, fingernail clippings, hair samples, and oral swabs can also be explored for potential predictive biomarkers. Follow up studies need to explore these additional biological media and test for their predictive capacity in observational studies. Finally, our study measured several biomarkers from the repertoire of lipid biomarkers; however we were limited in our measurement of biomarkers from the other major groups . The lack of representation of biomarkers from these other major groups may also be contributing to some degree to our observations of higher prediction capacity among lipid biomarkers compared to immune, protein oxidation, and growth factor biomarkers.Despite these limitations, our study contains several strengths to highlight. First, the study was conducted in a well-characterized birth cohort. Further, this study used high-sensitivity instrumentation to measure an extensive panel of biomarkers to assess predictors of preterm birth. Our findings provide insight on the utility of several biomarkers and groups of biomarkers to predict preterm birth. We integrated multiple statistical methods for high-dimensional data analysis that can be applied in future studies seeking to analyze a large amount of biomarkers. Another strength is that our differentiation of preterm birth subtypes provides greater clinical and physiological insight on the etiology of preterm birth. Overall our study presents new applications of statistical frameworks within biological context for future studies that seek to utilize maternal biomarkers to predict preterm birth.In conclusion, this study demonstrated that lipid biomarkers are good predictors of overall and spontaneous preterm birth. Our findings attempt to contribute a first step at prioritization of biomarker categories and eicosanoid enzymatic pathways for future studies that seek to predict preterm birth and inform precision health studies. Among eicosanoids, LOX and CYP450 products have the greatest performance of identifying overall and spontaneous preterm birth. We recommend replication studies to evaluate the consistency of our findings, and conclude that lipid biomarkers may have good utility in clinical settings to predict preterm birth.40.The LIFECODES prospective birth cohort enrolled approximately 1,600 pregnant women between 2006 and 2008 at the Brigham and Women’s Hospital in Boston, MA. Participants were between 20 and 46 years of age, recruited at less than 15 weeks gestation at the initial study visit, and attended up to 4 study visits  at which point they provided urine and blood specimens. At the initial study visit, questionnaires were administered to collect demographic and health-related information. Among participants recruited in the LIFECODES cohort, 1,181 participants were followed to term, and delivered live, single infants. This present study was cross-sectional and focused on urine and plasma samples collected at one study visit occurring between 23.1 and 28.9 weeks gestation (median = 26 weeks). The study sample included 58 women who delivered preterm (<37 weeks gestation), and 115 randomly selected women who delivered after 37 weeks gestation. Among the cases, there were 31 spontaneous preterm births and 25 preterm births associated with aberrant placentation, and 2 cases that could not be sufficiently categorized as either. This study received institutional review board (IRB) approval from the Brigham and Women’s Hospital and all participants provided written informed consent. All of the methods within this study were performed in accordance with the relevant guidelines and regulations approved by the IRB. Additional details regarding recruitment and study design can be found elsewhere9. We also measured angiogenic factors PGF and soluble fms-like tyrosine kinase-1 [sFlt-1] in plasma using the ARCHITECT immunoassays by Abbott Laboratories .Spot urine samples were collected and stored at −80 °C. Approximately 10 mL of blood was collected using ethylenediaminetetraacetic acid plasma tubes and temporarily stored at +4 °C for less than 4 hours. Afterwards, blood was centrifuged for 20 minutes and stored at −80 °C. Urine and plasma were subsequently analyzed for endogenous biomarkers. Supplemental Fig. 41. We measured for five oxidative stress biomarkers. The biomarkers total 8-isoprostane [8-IP] and 8-hydroxydeoxyguanosine [8-OHdG] were measured in urine samples by Cayman Chemical . Urine samples were hydrolyzed for deconjugation of 8-IP and then purified through affinity column chromatography prior to measurement with enzyme immunoassay. 8-OHdG was measured with direct dilution into buffer without purification using an enzyme immunoassay.The expanded panel of lipid biomarkers included 53 eicosanoids and lipid metabolites measured using a 6490 Triple Quadrupole mass spectrometer , set to a targeted multiple reaction monitoring mode. Eicosanoids were identified based on metabolite-specific fragmentation and corresponding retention time. Further details on instrument parameters and quality control can be found elsewhereo,o’-dityrosine [DY]. To quantify these markers, plasma protein was first precipitated from plasma samples and diluted with a phosphate buffer. Plasma samples were then delipidated, spiked with isotopically labeled internal standards, and hydrolyzed for 24 hours. The processed plasma samples were then analyzed for each protein oxidation marker via liquid chromatography electrospray ionization tandem mass spectrometry42.Three protein oxidative stress markers were measured in plasma samples, including 3-nitrotyrosine [NY], 3-chlorotyrosine [CY], and 5. Clinically, we defined another subset of preterm birth cases as those associated with aberrant placentation using the following criteria: (1) preterm birth resulting from the presentation of preeclampsia (encompassing onset of hypertension and proteinuria), or (2) intrauterine growth restriction  during pregnancy5.We defined overall preterm birth as delivery prior to 37 weeks gestation. Among the preterm birth cases, we categorized a subset as spontaneous preterm births based on the following clinical criteria: (1) preterm premature rupture of the membranes (PPROM), or (2) spontaneous preterm laborncases+controls = 138 for all preterm, ncases+controls = 121 for spontaneous preterm and ncases+controls = 110 for preterm birth associated with aberrant placentation. We first investigated the effects of single endogenous biomarkers on overall, spontaneous, and preterm birth associated with aberrant placentation. Measurements were log-transformed and then standardized with mean of 0 and standard deviation of 1. The effects were estimated from the model:In this study, we evaluated the associations of overall preterm birth, in addition to spontaneous preterm birth, and preterm birth associated with aberrant placentation subtypes with 65 endogenous biomarkers of interest. The subsequent analyses were restricted to individuals who had all information on covariates and biomarkers available: Y denotes an n × 1 vector of the outcome variable in separate logistic regression models where each preterm birth outcome was individually modeled to test for associations compared to term births. M is an n × 1 vector that represents the biomarker of interest. The covariate matrix Z contained age at the initial visit, race, education level, health insurance provider, and maternal BMI at the initial study visit. Age is a continuous variable and the rest of the covariates were categorical. Z further included specific gravity if M is a urinary biomarker (8-OHdG and 8-IP). To account for multiple testing and control the FDR, we applied the Benjamini-Hochberg procedure to the set of p-values obtained from Model 1 with FDR being 0.1 for each definition of outcome43. We also performed a sensitivity analysis by examining associations in unadjusted models.where Y and Z are defined in the same way as for Model 1, while M is now an n × m matrix of the biomarkers of interest with m being the number of biomarkers considered in Model 2. We applied adaptive elastic-net45, a regularized regression approach, to each of the three outcome definitions separately using the R package gcdnet. The estimates of the p × 1 vector β = T were obtained by solving:One of our study goals was to determine which of the 65 biomarkers were contributing most to associations with preterm birth in a multiple biomarker model:46 and ridge47 type penalty to perform variable selection with a correlated set of candidate predictors. The function h is an assumed loss function, and the the adaptive weights λ2) take values on a grid from 0 to 2, in increments of 0.1. Furthermore, we forced the covariates Z to always be included in the model. For each fixed λ2, the function automatically computes the solutions for a fine grid of λ1’s, the λ1 and λ2 that yielded the smallest 10-fold cross-validated misclassification error and used their corresponding coefficient estimates as adaptive weights.which uses both lasso41, or if they are parent compounds  DNAds Table . To inveL(β) is the likelihood function for Model 2, q is the total number of groups considered (in this case q = 5), pk is the number of predictors in group k, and ∥1 and ∥2 are L1 and L2 norm, respectively. The mixing parameter α and tuning parameter λ together controls both “groupwise sparsity” and “within group sparsity” of non-null biomarkers. We set α to be 0.95, which assumes strong overall sparsity but encourages grouping48. In a secondary sparse-group lasso implementation, we split the major group of lipid damage markers into five subgroups, which included groupings for the three enzymatic pathways, lipid parent compounds, and 8-IP on its own (q = 9). Since current R implementation of sparse-group lasso does not support the specification of non-penalized coefficients, we treated the group of covariates as an additional group48. The relative importance of the associations was evaluated based on the sequence of the path in which each group exits the model as the tuning parameter λ increased (the group exiting last being the most important).where 49 to achieve balance between cases and controls, which may improve the prediction of minority class (in this case preterm birth). We used three different prediction algorithms using: (1) logistic regression, (2) adaptive elastic-net, and (3) random forest. First, we fitted a standard logistic regression model (Model 2) with the coefficients being estimated by maximum likelihood to the resampled training data for all biomarkers organized by each major group, and each eicosanoid enzymatic pathway. This method serves as a benchmark for evaluating the performance in prediction. The group of lipid damage biomarkers  was excluded for this approach because the maximum likelihood estimates obtained from logistic regression were unstable due to the high dimension of predictors. Second, we trained the model by applying adaptive elastic-net to the training set for each major group of biomarkers, the process of which was the same as what was done on the whole data set. Building on this framework, we also applied the same adaptive elastic-net method to the training set where we focused solely on the lipid biomarkers differentiating the three enzymatic pathways and the parent compounds. Finally, going beyond parametric regression methods, we trained the model using random forest for all groups considered, where the number of variables randomly sampled at each split for the random forest method was determined using 10-fold cross validation. The logistic regression prediction approach is limited and becomes unstable in the presence of multicollinearity and high-dimensionality of covariates and predictors. The adaptive elastic-net prediction method has improved performance in the presence of multi-collinearity, however it is unable to account for non-linear relationships between predictors and outcome variables. Finally, the random forest prediction method is able to account for non-linear relationships and interactions among predictors.We evaluated the performance of all and grouped endogenous biomarkers in predicting preterm birth. Subjects were randomly divided into training set and validation set with a ratio of 70:30 for the respective comparison of overall, spontaneous, and preterm birth associated with aberrant placentation vs. term deliveries. The training set was resampled using the Synthetic Minority Over-sampling TechniqueFor all three prediction approaches, we obtained the predicted probability of the outcome of interest for each subject in the validation set using the optimal parameters determined by the training set. Subjects were classified as cases if their predicted probabilities were greater than 0.5 and controls otherwise. We calculated the misclassification error, sensitivity and specificity, the latter two of which are defined as the probability of correctly identifying the participants with and without preterm delivery, respectively. Over fitting can be a possible concern in the logistic regression prediction method; however over fitting is not a major concern in both adaptive elastic-net and random forest prediction methods. We also examined the ROC curve and computed the AUC to assess the performance of the final model.This study received institutional review board approval from the Brigham and Women’s Hospital and all participants provided written informed consent.Supplementary material


How was the whole range of gestational age at birth associated with socioeconomic outcomes in adulthood ?In this cohort study including 228 030 singletons, lower gestational age (<39 weeks of gestation) was associated with lower odds of high educational level and high personal income and increased odds of receiving disability pension and cash welfare benefits compared with individuals born at 40 weeks of gestation.These findings suggest that lower gestational age even within the term range may have implications for long-term opportunities and well-being as measured by socioeconomic outcomes in adulthood. The poor health outcomes associated with preterm birth are well established. However, it is less clear how small variations in gestational age, even within the term range, are associated with long-term opportunities and well-being, as measured by socioeconomic outcomes in adulthood.To examine the association of gestational age at birth with educational achievement, income, and primary source of income in adulthood.This Danish population-based, register-based cohort study examined all live-born singletons born in Denmark from 1982 to 1986 without congenital anomalies and who lived in Denmark at age 28 years. Data analysis was conducted from November 2, 2017, to June 15, 2018.Gestational age at birth in completed weeks (22-45 weeks).Educational attainment, personal income, and primary source of income at age 28 years.In a population of 228 030 singletons , 36.3% had a tertiary education at age 28 years. Among adults born at 22 to 27 weeks of gestation, 21.6% had a tertiary education, and 23.2% had an income in the highest tertile. Using 40 weeks of gestation as the reference, the adjusted odds ratio for tertiary education for individuals born at 22 to 27 weeks of gestation was 0.21  and the corresponding figures for 28 to 31, 33, 36, 38, and 43 to 45 weeks of gestation were 0.45 , 0.67 , 0.84 , 0.85 , and 0.93 , respectively. The adjusted odds ratio for highest income tertile for individuals born at 22 to 27 weeks of gestation was 0.66  and the corresponding figures for 28 to 31, 33, 36, 38, and 43 to 45 weeks of gestation were 0.80 , 0.77 , 0.89 , 0.95 , and 1.00 , respectively. All estimates were adjusted for sex, birth year, parity, maternal age, maternal education, and maternal country of origin.Shorter gestational duration even within the term range was associated with poorer socioeconomic outcomes in adulthood. While adults born at 35 to 38 weeks of gestation experienced only slightly increased risk of adverse socioeconomic outcomes, this may have a significant impact on public health, since a large proportion of all children are born in these weeks. This Danish population-based cohort study examines the associations between the entire span of gestational age at birth and socioeconomic outcomes, measured as educational achievements, personal income, and primary source of income, in young adulthood. However, much less is known about the long-term socioeconomic achievements of adults born early term. The aim of this study was therefore to examine the associations between the entire span of gestational age and socioeconomic outcomes in the Danish population, measured as educational achievements, personal income, and primary source of income in young adulthood. In addition, the hypothesis that parental socioeconomic position might act as an effect modifier of the association between gestational age and socioeconomic outcomes was investigated.The association between the whole range of gestational age rather than preterm birth and social and health outcomes in adulthood are less thoroughly investigated. Children born from 37 to 41 weeks of gestation have traditionally been considered a low-risk and homogeneous group.STROBE) reporting guideline. According to Danish legislation no ethical permission was required for register-based research; however, the study was approved by the local data protection authorities.In this longitudinal register linkage cohort study of all singletons born in Denmark from 1982 through 1986, individuals were followed from birth to age 28 years in the Danish national registers. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology . As we investigate socioeconomic outcomes at age 28 years, only individuals born in or before 1986 could be included as we had information on socioeconomic attainment up to 2014. Data from the Danish Medical Birth Registry14 were linked to data on education, income, and primary source of income from the Population Education Register,15 the Income Statistics Register,16 and the Employment Classification Module, respectively.17 Information on these socioeconomic variables was obtained in the calendar year a person turned 28 years old. Furthermore, information on the mothers’ education, age at birth, and country of origin was linked to the live-born singletons. The linkage across the different registers was enabled by the Danish system of unique person identifiers.All live-born singletons recorded in the Danish Medical Birth Register18 and congenital anomalies excluding minor congenital anomalies were defined according to the European Registration of Congenital Anomalies and Twins definitions.19 Furthermore, 11 804 individuals (4.8%) who did not live in Denmark throughout the calendar year they turned 28 years old were excluded  who lacked information on at least 1 of the variables of interest were excluded   with the following characteristics were excluded: individuals who died in or before the calendar year they turned 28 years old (n = 4100) and individuals with at least 1 congenital anomaly registered within the first year of life (n = 10 030). Congenital anomaly diagnoses were obtained from the Danish National Patient Register14 The length of gestation was estimated by ultrasonography examination, last menstrual period, or clinical examination.21 Gestational age in completed weeks of gestation was categorized into the following groups: less than 22 to 28, 28 to 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, and 43 to 45.Information on the main exposure of interest, gestational age, was obtained from the Danish Medical Birth Register.22 in the following categories: primary (ISCED level: 1-2), secondary (ISCED level: 3-4), and tertiary (ISCED level: 5-8). Information on annual disposable personal income  in the calendar year a person turned age 28 years was categorized into tertiles for each calendar year. In the Employment Classification Module individuals were assigned a primary source of income based on their most important source of income throughout the year, ie, the activity with the highest incomes.17 Primary source of income at age 28 years was categorized into the following 5 groups: employed, unemployed, cash benefits, disability pension, and others. The category of employed included employed and self-employed persons, and the category of unemployed included persons who had been unemployed for 6 months or more in a given calendar year.23 The category of cash benefits included people who could not support themselves or their families and could not be supported by other benefits.24 The category of disability pension included people with a substantial and permanent reduced working capacity.25 The category of others included people whose primary source of income were not from employment, unemployment benefits, cash benefits, or disability pension, and included people whose primary sources of income were study grants and sickness leave benefits.The main outcomes of interest were educational attainment, income, and source of income at age 28 years. The education variable was categorized according to the International Standard Classification of Education (ISCED) 2011 definitions26Other covariables of interest were birth year, sex, maternal age at birth, parity, maternal education 1 year before birth (categorized according to ISCED level), and maternal county of origin . The matP value for the interaction term between gestational age and maternal educational level did not reach statistical significance for any of the socioeconomic outcomes. The interaction terms were not included in the main analyses.Multinomial logistic regression models were used to examine the associations between gestational age and education, income, and primary source of incomes at age 28 years in the analysis population. Adjusted odds ratio (aOR) and unadjusted OR from the multinomial logistic regression models were presented with 95% confidence intervals. Based on a priori confounder identification, the following covariables were adjusted for: birth year, sex, parity, maternal age, maternal country of origin, and maternal education. The study explored any potential interactions between gestational age and maternal educational level on the socioeconomic outcomes by including an interaction term in the multinomial logistic regressions. Statistical significance for interaction was assumed at an α level of .05. The A sensitivity analysis was conducted in the oldest subsample of the population to test whether the associations differed if outcomes were measured at age 30 years. All statistical analyses were performed using SAS statistical software, version 9.4 (SAS Institute Inc) from November 2, 2017, to June 15, 2018.In the analysis population of 228 030 individuals, 4.0% were born before 37 weeks of gestation, 12.1% were born from 37 through 38 weeks of gestation, 74.6% were born from 39 through 41 weeks of gestation, and 9.2% were born after 41 weeks of gestation. The sex distribution was 49.4% women and 50.6% men .Adults born before 39 weeks of gestation compared with adults born at 40 weeks of gestation had higher percentages of nulliparous mothers, mothers with parity higher than 3, mothers younger than 20 years and older than 34 years at participants’ birth, mothers with primary education, and mothers of nonwestern origin .Overall, 36.3% of the individuals had completed a tertiary eduation. Among individuals born at 40 weeks of gestation, 36.8% had completed a tertiary education; the corresponding figures for individuals born at 22 to 27, 28 to 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, and 43 to 45 weeks of gestation were 21.6%, 26.2%, 30.1%, 31.1%, 29.8%, 30.4%, 33.5%, 32.0%, 34.0%, 36.3%, 37.8%, 37.3%, and 34.9%, respectively . The perOverall adjustment for potential confounders attenuated the associations  was associated with increased odds of disability pension and cash benefits, and decreased odds of having a secondary and tertiary education and being in the highest income tertile. Adults born at 41 weeks of gestation had similar or slightly better socioeconomic outcomes compared with adults born at 40 weeks of gestation. Adults born postterm did not differ from those born at 40 weeks of gestation in terms of income and educational level. However, increased odds of disability pension and unemployment were observed for adults born after 42 weeks of gestation.6 Adults with at least 1 indication of disability were excluded from most of the analyses in the Swedish study, and this exclusion might explain the different findings since a strong gestational age gradient in individuals with an indication of disability was observed. In the present study we did not exclude individuals with indications of disabilities since disability may be a consequence of lower gestational age.2To our knowledge, this is the first study to show associations with early term birth and worse socioeconomic outcomes in adulthood. A previous Swedish study that investigated early term birth did not observe significantly poorer socioeconomic outcomes in adulthood among these adults compared with adults born from 39 to 41 weeks of gestation.27 that found that preterm birth and/or low birth weight was associated with lower educational qualifications and an increased likelihood of welfare benefits. Previous studies also found that adults who had been born preterm were less likely to have higher incomes4,6 and more likely to receive disability pension.8 We did not find an association between preterm birth and unemployment in our study. This finding was consistent with previous Nordic studies.8 These findings were perhaps surprising since the unemployment rate often differs by educational level28 and gestational age differences were observed for educational level, but it could be explained by selection of the most health challenged and/or socially challenged preterm offspring into other welfare benefits.Our findings regarding the socioeconomic outcomes of adults who had been born preterm corroborate a recent meta-analysis29 suggested that the association of preterm birth with school performance was more severe in those with lower parental socioeconomic position. By contrast, our test for interaction between gestational age and maternal educational level on the 3 socioeconomic outcomes did not suggest that maternal education was an effect modifier. However, it cannot be ruled out that effect modification by this or other measures of parental socioeconomic position would be present in some strata.We did not find that preterm birth had differential socioeconomic consequences in adulthood on the basis of maternal educational level. A previous Swedish study17 The obstetric and socioeconomic data were obtained from the routine population-based data, which obviates recall bias and limits selection bias. Linkage across several Danish registers at an individual level made it possible to follow individuals from birth into young adulthood. The use of several indicators for socioeconomic position in young adulthood was an additional strength of this study.The study was based on routinely collected population-covering data and examined socioeconomic achievements across the whole gestational age spectrum. The Danish registers used in this study were nationwide and had a high level of completeness.30 and registration of gestational age.21 However, the prospective design reassures that this misclassification is nondifferential. Individuals with implausible relationships of gestational age and birth weight were excluded to reduce the problem of registration errors. A study reported that the majority of children in the Medical Birth Register had reported 1 additional week of gestation compared with the gestational age reported in the medical records in a sample from 1982 to 1988.21 The distribution of discrepancies in gestational age was the same across the whole range of gestational age and thereby this potential misclassification may have shifted the findings of this study to higher gestational ages, but would not have altered the observed associations.The accuracy of gestational age estimates is likely to be influenced by distinct methods of estimating gestational age31 and as a consequence we may not have fully accounted for parental socioeconomic position. However, in a previous study we found maternal education to be the strongest socioeconomic indicator for preterm birth.32 A potential limitation was the changing gestational age distribution over time, whereby the proportion of children born before 37 weeks of gestation was higher in the Danish population of live-born children born from 2012 to 2016 compared with our study population .33 Each of these factors could potentially be associated with poor neurodevelopmental outcomes.33Future studies should focus on identifying mechanisms underlying the association between gestational age and socioeconomic outcomes. Although beyond the scope of our study, some of the plausible mechanisms may be maturation outside the uterine milieu, the morbidity associated with lower gestational age, and the underlying causes of premature birth.Given that so many powerful factors affect socioeconomic position from birth to adulthood, the findings of poorer socioeconomic outcomes of adults born as little as 2 weeks before term (40 weeks of gestation) are noteworthy. The study’s findings suggest that by addressing gestational age as a continuum, one may provide insight into the association between gestational age and long-term outcomes, which could not have been obtained by investigating the differences between children born at the earliest gestational ages and children born at term. If these findings were causal, they would be of relevance to clinicians and for future research since a large proportion of children are born in the weeks before term (40 weeks of gestation). To address causality, randomized trials with long-term follow-up of labor induction vs postponement of labor induction are needed. In addition, the study’s findings emphasize the importance of early life factors for later life and further emphasize the need for tackling the socioeconomic gradients in preterm birth.Our study shows that not only adults born before 37 weeks of gestation but also adults born at 37 and 38 weeks of gestation have increased risks of several poorer socioeconomic outcomes including educational level, personal income, and primary source of income at age 28 years.


Birth plans are meant to be a declaration of the expectations and preferences of pregnant woman regarding childbirth. The My Prenatal Care app engages pregnant women in an educational intervention for a healthy pregnancy. We hypothesized that users’ positive perception of an in-app birth plan is a relevant step for establishing direct communication between pregnant women and the health care team, based on an online report available on the app.This study aimed to evaluate pregnant women’s perception about the communicability of birth-plan preparation using a mobile app.This was an observational, exploratory, descriptive study. The methodology was user centered, and both qualitative and quantitative approaches were employed. The tools of the communicability evaluation method were applied. Overall, 11 pregnant women evaluated their experience of using a birth-plan prototype interface. The evaluation was performed in a controlled environment, with authorized video recording. There were 8 task-oriented interactions proposed to evaluate interface communicability with users when using the Birth Plan menu. For evaluating perceptions and experiences, a survey with structured and open-ended questions in addition to the free expression of participants was conducted. The primary outcomes assessed were interface communicability and user’s perception of the Birth Plan prototype interface in the My Prenatal Care mobile app. Secondarily, we involved users in the prototyping phase of the interface to identify bottlenecks for making improvements in the app.Regarding users’ performance in accomplishing previously prepared tasks, we found that 10 of 11 (91%) women were capable of completing at least 6 of 8 (75%) tasks. A positive relationship was found between the number of communicability problems and the success of completing the tasks. An analysis of the records revealed three communicability breakdowns related to the data entry, save, and scrollbar functions. The participants freely expressed suggestions for improvements such as for the save function and the process of sharing the birth-plan form upon completion.Users had a positive perception of the Birth Plan menu of the My Prenatal Care app. This user-centered validation enabled the identification of solutions for problems, resulting in improvements in the app. A birth plan is a description of a pregnant woman’s expectations and preferences regarding childbirth ,2. PlannMobile apps related to pregnancy, birth, and childcare are important information sources for users, as they combine education and functionalities of communication to support the self-management of health . App adhThe My Prenatal Care app  was creaThe human-centered design and development of systems require that apps be made usable and useful by focusing on the users . Usable This observational, exploratory, descriptive study employed an interdisciplinary approach combining health and information sciences. The methodology was user centered and employed qualitative and quantitative approaches to assess pregnant women’s experience of using the Birth Plan menu of the My Prenatal Care mobile app. Pregnant woman who agreed to participate in the study individually answered a semistructured questionnaire . Their rTo identify the points of communication breakdown, task-oriented interactions were analyzed by two of the three steps in the communicability evaluation method—tagging and interpretation. Communication breakdowns were defined as disruptions occurring during user interaction based on the computational artifact acquired from video analysis, according to a prespecified set of utterances . TaggingThe research protocol was approved by the Ethics Committee of the Universidade Federal de Minas Gerais, with the national register number CAAE-68076617.2.0000.514 in Plataforma Brasil. All participants were informed that participation was voluntary and were provided the details of the study. To ensure voluntary participation, they were allowed to withdraw their consent at any time, without any consequences. Written informed consent was obtained from each participant. To avoid influencing the users’ perceptions positively, they were not provided any direct or indirect gratification. Additionally, there was no burden on the participants, except their time.The participants were recruited from the university’s prenatal care center. High-risk pregnancies are often referred to this public and teaching health care institution. Data were collected from December 2017 to January 2018. The participants attended institutional focus groups led by obstetric nurses before enrollment in the research. During these group sessions, the importance and objectives of elaborating a birth plan and preparation for birth were discussed. This educational approach is routine in this unit and is not part of the methodology.Considering the significant variance in the computer skills of our population, this study used a convenience sample of 11 participants to evaluate users’ perceptions of the birth-plan interface tested in this study. Based on a previous report, the detection of usability problems requires at least five users, because the function of the number of users tested or the number of heuristic evaluators is modeled as a Poisson distribution . AccordiA total of 15 women expressed interest in participating in this study during their prenatal care visit. Three women dropped out of the study citing fatigue during the ethics information sessions before communicability testing. One pregnant woman was excluded during the tests because of visual impairment. The final sample comprised 11 participants.We conducted a pilot evaluation to prepare a controlled video-shooting environment. Four women (of whom two were not pregnant) who were not part of the main sample were invited to validate the setting, equipment, and instruments prepared for the monitored interaction between the participants and the interface. First, the equipment and mobile devices were tested and adjusted for effective recording of the interactions in two nonpregnant women. Second, data-collection instruments to be used for the participants and for evaluation of communicability were tested in two pregnant women. Poor image quality revealed the need to replace one video camera, while the data-collection instruments were considered adequate. We captured images during the test from four different angles using one tablet (a 7-inch Samsung tablet) and two Sony high-definition digital cameras supported by tripods and software. During the execution of the predefined tasks, one angle captured the manipulation of the mobile device, one recorded the face, the third recorded and entire body. The AZ-Screen-Recorder software  continuously captured images of the mobile interface during the experiments. Further, observational notes were taken during filming.In order to identify and adjust human-computer interaction problems, we used the communicability evaluation method. The focus was on the quality of the user interaction while using the Birth Plan prototype interface. The researcher verbally and in writing advised the participants about the task to be executed in the app. The participants were free to talk during the test and received a fictitious case report  based onThe experimental scenario was exclusively used for testing in order to avoid interruptions and displacement. No help was provided by the researchers or third parties. Identical task-oriented interactions were used for each participant individually. The evaluation started with a fictitious case in which the strategy for the communicability test was implemented by minimizing personal involvement or deep reflections. This procedure allowed the users to work impartially only on the tasks without personal opinions.Video record analysis, tagging, and interpretation were performed for identifying breakdowns in communicability and problems in human-computer interaction by detailing the moments and interfaces in which they occurred ,16. We cThe video recordings and observation notes were reviewed repeatedly for analysis and tagging using the Filmora software . Communication breakdowns were analyzed to measure interface communicability for the users. Two authors (JC and IO) judged the participants’ interaction with the interface. All video material and notes were first analyzed individually and then combined based on consensus between judges, following the communicability evaluation method . CommuniAn individual in-person evaluation assessed users’ experience regarding the interaction with the system. We conducted a semistructured survey with one question on the difficulties experienced in completing the test and two open-ended questions allowing for free expression to provide suggestions and record experiences/opinions . AdjectiAll data were stored in an Excel database and analyzed in IBM SPSS 22.0 . Descriptive statistics explored the characteristics of the participants, summarized according to the nature of the variables. The numerical variables were described using minimum and maximum values, average, and SD. The variables are presented using absolute and relative frequencies. The responses for the difficulties experienced in performing the tasks were presented in terms of absolute and relative frequencies. The qualitative evaluation described how positive the users’ experience was in interacting with the app.The age of the 11 pregnant women enrolled in this study ranged from 18 to 39 years, with an average age of 30.7 (SD 6.5) years . Two parRegarding the obstetric profile of the participants, gestational age ranged from 17 to 39 weeks of gestation and almost half of the participants were parous . However, only half  of the parous participants classified their previous childbirth experience as good. None of the participants had previous experience in making a birth plan.All participants owned a smartphone, and 10 of 11  had access to mobile internet. The same frequency was observed for experience with a device with an Android-based operating system. The duration of daily smartphone use was 3 hours or more for 6 of the 11 women (55%), while 4 of the 11 (37%) used their phones for more than 5 hours per day. WhatsApp was the most frequently used app . Seven  participants reported no experience with health and well-being apps, while three had used an app to support their present gestation.Task 8 was the only task that was completed by all the participants . It pertThe number of tags found in the analysis of the video recordings, after considering the observers’ notes, is presented in The most-frequent tag—“What happened?”—was associated with starting the “Save” action 16 times. We observed repeated attempts to use the “Save” action after finishing tasks because the provided feedback was not perceived by the user. The second most–frequent tag, with 14 instances, was “Where is it?” This tag symbolizes the difficulty of the user in finding functionalities in the interface to perform the required actions [The analysis of the execution of Task 4 presented nine instances of tags. A higher difficulty could be attributed to the positioning of this entry in the menu options. We intentionally asked the participants to localize this entry in the bottom edge of the menu to analyze the interaction between the users and the scrollbar. We noticed a positive relationship between the number of communicability breakdowns and success in completing tasks, except for Task 8, which had eight instances of tags. A breakdown of communication occurred because the users chose the option “Share” in the Birth Plan menu; the symbol that indicated loading lacked text and was not sufficient for users to understand its function. Another point of breakdown was when the users did not immediately realize that Ana’s friend (a fictitious contact for sharing the birth plan) could be one of their contacts.Task 7 was not assigned any tag, and 91% (10/11) of the users completed the task. Tasks 1 and 4 were associated with the highest number of tags, indicating a higher frequency of communication breakdown compared to the other tasks. These tasks had the lowest completion rate . Task 1, which received 17 tags, pertained to the first contact with the Birth Plan prototype interface. Therefore, the initial difficulty experienced by the users was expected. However, we found communication breakdowns in two other instances: One was related to a difficulty in finding the option “Phone Number” in the Birth Plan menu, and the other was related to the feedback of the save function.Nine participants  reported having no difficulties when they were preparing a birth plan using the app. Two of them reported impairments associated with their ability to handle smartphones, but the impairments pertained to their ability, in general, and not solely during the study. They expressed spontaneous phrases about their experience of and opinion about the Birth Plan prototype interface . The conIn this study, we validated a birth-plan interface in terms of its communicability based on the interactions and perceptions of pregnant users for creating an in-app birth plan. Our main finding was the positive perception of users regarding birth-plan preparation in the app. An advantage of using a mobile app for creating and sharing birth plans is that it is promptly available for future retrieval anywhere the birth may take place. This document is personal to each woman once she has expressed her wishes and should be reviewed during every follow-up visit and modified, if any complications arise . PlanninTo play an active role in identifying a pregnant woman’s needs, birth plans are being introduced during prenatal care by involving women in discussions with future care providers and listening to their desires and flexibilities regarding the birth experience . An editWith respect to the complete execution of tasks and based on the analysis of the communicability breakdowns identified by the communicability evaluation method, the results pointed out the areas that could be enhanced in the app. Regarding improvements in the interface for solving communication problems, we introduced some modifications. The “Save” message now appears in a new window that opens automatically at the center of the screen, thereby signaling the saving process. Another modification was the appearance of the text message “Loading” when the “Share” command is used. For better interaction with the scrollbar, we plan to use an animation to signal the bar.Our findings revealed favorable outcomes for the overall user experience. Most of the pregnant users did not report difficulties when performing the tasks with the Birth Plan prototype interface. The user experience survey revealed that all of them expressed good opinions, and “I liked it,” “Interesting,” and “Communication” were some of the positive aspects that the users associated with the app . ImpairmAnother point to highlight is the sharing of clinical data among systems. Health data include relevant information that might support medical decisions. EHRs demand essential properties such as sharing data with semantic interoperability, preserving flexibility for modifications, and fostering efficacy to promote communication among stakeholders . CrediblThis study had some limitations. Although the sample was considered adequate to validate tests of human-computer interaction, it did not allow for inferential statistical analysis. Regarding penetrability, technologies directed toward pregnancy care require flexibility in order to support different models of birth, specific circumstances, and cultural meanings of childbirth. We can assess the scope and usefulness of this tool only by monitoring the adoption of the app. In the future, we wish to conduct another study involving different centers, cultures, and languages, as the app is currently offered in only three languages. Furthermore, we would like to compare pregnant women’s perceptions when birth plans are declared in a traditional manner such as orally, in writing, or through information technology.Another limitation was the controlled experimental scenario, which may not reflect real-world situations. However, the present study avoided bias in analysis owing to differences in the speed of the internet connection and smartphone performance.An important factor is the limitation of the use of technology in a health care setting. During pregnancy, it is advisable that prenatal care be provided by health professionals directly to pregnant women. Any impact of a birth plan in improving the quality of care cannot be attributed only to the app, but also to best obstetric practices .Mobile apps have become a primary source of health guidance for people. Other reports with similar target users have revealed that internet access through websites or mobile apps is useful in helping women adopt a healthy lifestyle during pregnancy and in self-managing their prenatal care ,27. In fThe interface for birth plan–preparation tested in this study, which was provided through a mobile app, was perceived positively by pregnant study participants. Its user-centered validation enabled the identification of new solutions to solve communication problems, resulting in improvements to the app. This experience revealed real-world perspectives on the communicability for creating an in-app birth plan and on supporting information sharing among pregnant women and the health care team.


We applied generalized additive models for location, scale and shape (GAMLSS) when calculating the birth weight percentiles, and calculated percentiles for monochorionic and dichorionic twins separately. We next used data collected between Jan 1st 2018 and Apr 30th 2018, encompassing 12,371 live births, to calculate the SGA and LGA ratios using birth weight references in Australia, South Korea and China (based on birth defects surveillance system) and birth weight percentiles calculated in this study. Compared to dichorionic twins, monochorionic twins had lower birth weights at 25 to 42 weeks of gestation. The calculated SGA and LGA ratios were relatively stable compared to the other references.Mean birth weight of twins is known to be lower than that of singletons, however, southern China lacks a twin-specific birth weight reference. In this paper, we use data from the Birth Certificate System in southern China, collected between January 1 Twins have higher risks of preterm birth, perinatal morbidity and mortality2. Twins account for 2–4% of all infants, and the problems associated with twin pregnancies have attracted increased global attention. According to a report from the National Health and Planning Commission in China, the twin pregnancy rate increased by 4.1% in 20163. Chorionicity complicates twin health further. The risk of adverse pregnancy outcomes  and complications of fetus during pregnancy (e.g. twin-to-twin transfusion syndrome) is higher among monochorionic twins than among dichoroitic twins4. Therefore, chorionicity must be taken into account when establishing birth weight references for twins.In recent years, due to the development of assisted reproductive technologies, the twin pregnancy rate continues to rise6. SGA and LGA are associated with increased perinatal and infant mortality and morbidity, as well as long-term health problems. Twin birth weights were consistently lower than those of singletons7. In addition, multiple pregnancies are a risk factor associated with SGA8. Therefore, proper use of birth weights reference percentiles to classify birth weight is of great significance for clinical work and research.Birth weight is still the most commonly used indicator of fetal development. Infants are commonly defined as SGA or LGA if their birth weight percentile falls below the 10th percentile or above the 90th percentile of the reference standard13. Findings in these countries have demonstrated the importance of the development of national birth weight standards for twins. Researchers have suggested that gestational age-specific birth weight reference percentiles should be updated every 5–10 years1. However, there is still no reference standard for twin birth weights in southern China.Several countries, including Japan, Australia, South Korea, south India, Norway and the United States of America have developed population-based twin birth weight references to assist in accurately evaluating the growth of twinsThe current study aims to construct the sex- and gestational age (week)-specific birth weight reference percentiles for twins born in southern China, stratified by placental chorionicity (monochorionic and dichorionic placentation).All birth data were obtained from the Guangdong Provincial Birth Certificate System between Jan 1st, 2014 and Dec 31st, 2017. The system covers more than 1900 medical institutions and collects all information about mothers and infants. After birth, maternity medical workers place newborn infants on electronic scales to obtain stable weight data (weighing accuracy is within 1 g). In some cases, health care attendants or midwives fill in the newborns’ information in the regional maternal and child information system. The system sets logic correction to ensure that the entered birth weight falls within a feasible range. Finally, regional maternal and child information are uploaded to the Guangdong Provincial Birth Certificate System. The Chief of Midwives and the Chief of Physicians in hospitals then confirm the information entered into the data system. Before the birth certificate is issued, the Department of Medical Administration and parents are also asked to confirm the birth information. All of the information is verified by medical professionals. The birth registry database includes the child’s date of birth, gestational age (week) at birth, birth weight, infant sex, parents’ ages, registered residence, method of delivery and placenta chorionicity, etc. From the database, we obtained 161,134 cases of twins. We excluded stillbirths (48 cases) and deaths within seven days (10 cases), which together accounted for about 0.04% (58 cases) in all twins. The final analytical sample included 161,076 twin births. Because this study is based on administrative data collected from a large population, it was not possible to obtain informed consents; however, the study was reviewed and approved by the Ethics Committee of Guangdong Women and Children Hospital.We analyzed the raw data of all twin newborns . The gestational age (week) was determined by combining mother-reported last menstrual period, ultrasound examination, and postnatal gestational age (week) assessment. The chorionicity of the placenta was judged by ultrasound data collected during the first trimester (about 6~7 weeks of gestation) and confirmed by data collected during examination of the placenta after birth.15. The GAMLSS method allows modeling of various kurtosis asymmetric distribution and the estimation of smooth percentiles to establish birth weight percentile curves for newborns of both genders. According to Cole’s reports16, a sample size of n >1000 is needed to use the GAMLSS technique to fit a curve. The Schwarz Bayesian criterion, which entails stricter curve smoothing, can be used to judge the pros and cons of the model, as well as to ensure the smoothness and accuracy of the model. GAMLSS is based on the LMS method with a specific distribution of . We used Box-Cox t (BCT) to model birth weight, a method that combines Box-Cox-Cole-Green (BCCG) with the Box-Cox-power-exponential (BCPE) distribution. Note that we take into account the skewness and kurtosis of the data to express the value of the predictor. In addition, we made the model residuals better modified and the shape of the curve tends to be smoother. Model selection was based on the generalized Akaike Information Standard (G-AIC). That is, we selected the model with the smallest GAIC value. The smoothed data were represented by birth weight percentile curves. The curves appeared in intervals of one gestational week. We estimated mean birth weights and corresponding standard deviations for twins at the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentiles from 25 to 42 completed weeks based on the smoothed, estimated curves. The percentiles were estimated separately by infant sex  and by chorionicity. SGA and LGA were defined as birth weights below the 10th or above the 90th percentile values at a given sex- and gestational week, respectively.Birth weight percentiles were created by using the Lambda Mu Sigma (LMS) method, which were fit using the GAMLSS package, based on the assumption that birth weight had a Box-Cox Cole and Green (BCCG) distributionNext, we used twin birth weight data collected between Jan 1st, 2018 and Apr 30st, 2018, encompassing 12,371 twin births, to verify the reliability of the four standards. We accomplished this by calculating the SGA ratio and the LGA ratio according to the standards’ 10th and 90th percentile values. If standards are reliable, the gestational age (week)-specific SGA and LGA ratios should fluctuate around 10%. We also compared the SGA and LGA ratios we generated to those generated using birth weight references from Australia, South Korea and China (established based on a birth defects surveillance system). Since birth weight may differ by race and ethnicity, the birth weight standards from other countries may differ from those we produced. Moreover, given that birth weights in China may have changed since the implementation of the two-child policy in China in 2016, previously produced birth weight standards in China may be outdated. In both cases, this could result in inaccuracies in the classification of infants as SGA or LGA.The GAMLSS package (version 5.0.6) for R statistical software (version 3.4.2) was used for analysis.As showed in Table rd,10th,25th,50th,75th,90th, and 97th percentiles in Table Table Table 17. The low birth weight of monochorinic twins can be attributed to a reduction in weight due to a shared placenta, as well as to reduce effectiveness of the placenta18.In this study, we constructed new birth weight percentage curves for twins born in southern China. We have estimated percentage curves separately by chorionicity in order to account for chorionic membranes during twin births. Our comparison of percentile curves by chorionicity showed that birth weights of dichorionic twins were higher than monochorionic twins at 25 to 42 weeks of gestation. This finding is consistent with research conducted in south India and the US17, while the East Flanders Prospective Twin Survey (EFPTS) found that the most rapid period of infant weight gain occurred between 32 weeks and 34 weeks, with 156 g gained per week19.The average birth weight of male infants is greater than that of female infants for both monochorionic twins and dichorionic twins. The overall pattern of change in birth weight over gestational age is characterized by a rapid increase in birth weight up until week 37, followed by a reduced rate of change afterward. Both male and female infants grew at the fastest rate between 34 and 35 weeks, gaining an average of 192 g and 182 g per week, respectively. Studies of twin pregnancies in the US have found that twin infants have the fastest weight gain between 32 weeks and 34 weeksBecause of improvement in medical care facilities and nutrition in China, the proportion of twins with fetal growth restriction has declined, while perinatal survival has improved. Furthermore, due to the large sample size used in our analysis, the birth weight standard we have produced can shed new light on the current situation of twins in southern China.17. In particular, fetal growth appears to differ for twins with monochorionic and dichorionic placentation. Until now, classification of chorionicity was not established for twin birth weight standards in southern China.According to the twin birth weight standard we have constructed for southern China, the highest prevalence (13.3%) of SGA was observed at 41 weeks of gestation, while the lowest (9.1%) was observed at 26 weeks of gestation. Relative to the other three standards, our standard led to a more stable estimate of the prevalence of LGA, which ranged from 6.7% to 11.5%. If we were to instead use one of the other three standards, we would likely misclassify SGA and LGA across all gestational age groups. In particular, the other standards lead to very different estimates of the SGA rate between 39 and 40 weeks of gestation. Compared to southern China’s twin birth weight standard, a smaller number of twins were classified as LGA by the Australian and Korean standards. However, a larger number of twins were defined as LGA if we were to use the Chinese standard (based on birth defects surveillance system). This suggests that twin growth standards for healthy twins developed in other countries are not applicable to the population of southern China. Moreover, it is important to regularly update the reference, in order to identify changes in birth weight distributions of twins over time. In addition, previous research has suggested that chrionicity should be taken into account when assessing twin fetal developmentDue to the lack of appropriate reference tools, birth weight percentiles for singletons are commonly used in clinical practice in China. In this study, the use of a large, nationally representative population-based sample of twins ensures a more representative and accurate estimate of percentiles.21. It has been suggested that preterm births should be assessed using estimated utero fetal growth trajectories rather than birth weight percentile, given that preterm neonates are likely affected by fetal growth restriction20. However, it is difficult to estimate utero fetal growth weight, due to challenges in obtaining accurate measurements, including estimates for fetal weight calculations and the formulas needed for the calculations21.Unfortunately, we did not collect data on environmental factors that may have affected the pregnant women and fetuses in the study, including socio-economic conditions, diet or nutritional status. Therefore, we cannot directly analyze the relationship between environmental factors and birth weight distributions. Secondly, as with other population-based studies, our data are based on birth registry data, rather than longitudinal measurement of the development of the same fetuses over the course of pregnancy. That is, we have not measured in utero fetal growth. Birth weight percentiles are not the same as intrauterine growth percentiles in that birth weight percentiles do not reflect fetal growth but rather size at birth. The birth weight of premature babies may be affected by the pathological process leading to premature birth and the developmental status during the period of extrauterine growth to full term may be different from that of intrauterine growth until full term


AbstractSalixsuchowensis have been addressed by different authors with varying opinions. However, these efforts were flawed by a lack of observation of relevant specimens. Accordingly, we carefully checked relevant publications and specimens both through internet databases and herbarium visits. Here, we thoroughly review the nomenclatural history of Salixsuchowensis in light of the new definition of a gathering in the Shenzhen Code. We conclude that this name was validly published in the original publication in 1963. Furthermore, a lectotype is designated for the precise application of the name. We hope this article will offer guidance for interpreting similar cases.The nomenclatural problems of  Salix L.  is variably estimated to include 350–520 species, which are widely distributed in temperate and boreal regions of the Northern Hemisphere with a few species in Africa and South America  and “C.T. Yang 20641 (♀)”, as type. Both S.suchowensis was not validly published by Salix species ” appears to represent a later renumbering of some female duplicates of C.T. Yang 20640. Therefore, S.suchowensis was validly published with the citation of a single gathering  were cited. Two collection numbers conserved in NF were designated as types with female (“C.T. Yang 20641”) and male branches (C.T. Yang 20640), respectively.When the name Tokyo Code (J.L. Guo 89012 (NF) as the holotype. However, the collection J.L. Guo 89012 (♀) (see discussion below) was not cited in the publication of J.L. Guo 89012 (GAUF) is amongst the original material cited by Populuswenxianica Z.C. Feng & J.L. Guo”, which was not validly published but was validated by J.F. Liu 88001 (GAUF) as type. Zhu’s citation of locality data for J.L. Guo 89012 “TYPE: China. Jiangsu: Nanjing, J.L. Guo 89012” differs from Salixsuchowensis does not occur in Gansu  in the Herbaria of ChinaA Catalogue of Type Specimens ( (20641. T(♂): NFU”, as the type of Salixsuchowensis (C.T. Yang is unquestionable. Neither Jin “Jin & Chen” (1994) nor 20641 contained fragments with female, not male, inflorescences. Despite this, the restriction to a single gathering and herbarium would suffice for valid publication . Therefore, of China : 599. Thhowensis . The colSalix deposited in NF .After checking all specimens of one Fig.  is compoone Fig. . All areThe collector C.T. Yang was a colleague of W.C. Cheng who worked a few years for NF then left for the Security Department of Nanjing Forestry University. The location “树木园 [Arboretum]” added by hand to typed herbarium labels is consistent with the handwriting of R.B. Chen, another colleague of W.C. Cheng. This information was obtained from a manager of NF (pers. comm.).Salixsuchowensis, from the Arboretum in 1956 and he participated in the publishing of Cheng’s Dendrology [I & II] in 1961 and 1964 (C.T. Yang 20641 (♀)” in the protologue of S.suchowensis was labelled C.T. Yang 20640 (♀) in the herbarium and, while annotating specimen labels, also “corrected” the collection number to match the protologue. The ink used for both annotations is similar. It is not possible to determine with certainty who changed the specimen numbers, nor when. However, the typed labels show that C.T. Yang 20640 was originally intended by the collector to include both male and female duplicates. This makes it unlikely that Yang himself was responsible for the later renumbering of some  of the female duplicates, which, if done by another worker, was inappropriate. Since Art. 9.2 and Ex. 3 of the Shenzhen Code permit obvious errors in type citations to be corrected, Cheng’s citation should be corrected to “Kiangsu: C.T. Yang 20640, Typus fl. ♂ & ♀!; C.T. Yang 10045; R.L. Chao 20515”. Under Art. 40, Note 1, all eight specimens of C.T. Yang 20640 are therefore syntypes of the name.R.B. Chen collected material, later labelled as and 1964 . TherefoS.suchowensis had originally been given two collection numbers , as cited by Salixsuchowensis in The “Shenzhen Code” has clarified the definition of a “gathering” as “a collection presumed to be of a single taxon made by the same collector(s) at the same time from a single locality” (Art. 8.2 footnote). Duplicates given different field numbers or collecting numbers, but collected by the same people at the same time and place, can still be treated as a single gathering . Even if the original material of Salixsuchowensis does not match any existing duplicate, because neither of the duplicates annotated as “20641” are male. Therefore, this listing was insufficient to designate any of the 8 syntype specimens of C.T. Yang 20640 at NF as lectotype. The same can be said for C.T. Yang 20641” as “holotype”. The attempted designation of type by Code : 4. 1963B11D84EBCEF35A69B9A977A24593F319(designated here). CHINA. Jiangsu: Nanjing, Arboretum of Nanjing Forestry University, 26 March 1954, C.T. Yang 20640 . — For image of lectotype, see Fig. Shrubs. Branches yellowish-green or purplish-red, glabrous; branchlets sparsely tomentose at first, becoming subglabrous. Buds glabrous. Stipules linear to lanceolate, 0.96–1.42(–2.5) cm; petiole 0.3–1 cm, margin remotely glandular dentate, pubescent to glabrous; leaf blade lanceolate, 5.17–12.25 × 0.63–1.7 cm, abaxially pale, both surfaces glabrous, tomentose when young, adaxially dull green, base cuneate, margin glandular denticulate, apex shortly acuminate; lateral veins diverging from midvein at 45–90°. Catkins before leaves emerge, densely flowered. Male catkin terete, 2.2–4 cm × 0.4–0.67 cm, sessile or subsessile, with scale-like leaflets at base; rachis grey tomentose. Female catkin up to 3.43 cm at maturity, sessile or subsessile, with scale-like leaflets at base. Floral bracts long obovate, abaxially villous, apex obtuse-rounded, purple black distally. Male flower: glands adaxial; stamens 2, connate throughout, anthers yellow or reddish-purple. Female flower: ovary conical, densely grey tomentose, ovules 3–7; stipe short to absent; style conspicuous; stigma 2-cleft. Capsule pilose.Flowering from March to April and fruiting in April and May.Habitat. Along rivers, stream-sides, or cultivated; near sea level to 900 m a.s.l.Beijing, Hebei, Henan, Jiangsu, Shandong, N Zhejiang.Beijing: Miyun County, Dajiaoyu, 5 May 1951, Y. Liu 1507-8 (PE); Yudu Mountain, 900 m a.s.l., 11 June 2019, F.Y. Guo, Y.M. Wu & D. Liu G2019061105 (BJFC). Hebei: Daming County, Dongcao, 100 m a.s.l., 3 June 1972, Han 165 (PE). Henan: Song County, Xiasi, 25 September 1956, Henanshenglinyeting 1217 (PE). Jiangsu: Nanjing, Arboretum of Nanjing Forestry University, 12 April 1954, C.T. Yang 20645 (NF); ibidem, 26 May 1956, R.B. Chen s.n. (NF); Xuanwu Road, 19 May 1956, C.T. Yang 10045 (NF). Shandong: Gudao, Huanghenongchang, 16 July 1959, T.Y. Zhou 5412 (NAS). Zhejiang: Zhuji, Paitou, 24 September 1934, Y.X. He 2952 (NAS).—CHINA.