The National Birth Defects Prevention Study

Parental Mental Health Conditions and Infant Health Outcomes Among Military Families

INTRODUCTION

Little is known about the effects of parental mental health burdens during pregnancy on infant health among military families, who are subject to various stressors unique to military life. The present study leveraged infant data from the DoD Birth and Infant Health Research (BIHR) program and self-reported parental survey data from the Millennium Cohort Study (MCS) to examine associations of parental mental health conditions with adverse infant health outcomes.

MATERIALS AND METHODS

Subjects included singleton infants captured in BIHR program data, born between July 2001 and December 2012, to MCS women and men who completed a baseline or follow-up survey from 1 year before pregnancy start through infant birth date. Survey assessment included mental health screenings and behavioral health measures (e.g., smoking and alcohol use). Mental health exposures included post-traumatic stress disorder, major depression, and panic/anxiety disorder and were assessed as "any mental health condition" (yes or no) and "count of mental health conditions" (0, 1, 2, or 3). Infant outcomes included birth defects, low birth weight, and preterm birth and were assessed individually and as a composite measure of "any adverse outcome." Descriptive statistics were calculated for the maternal and the paternal study populations stratified by exposure status. Log-binomial models estimated risk ratios (RRs) and confidence intervals (CIs) for all outcomes.

RESULTS

Among 9489 infants born to MCS women, 1006 (10.6%) were born to women who screened positive for any mental health condition; 571 (6.0%), 268 (2.8%), and 167 (1.8%) were born to women who screened positive for 1, 2, and 3 mental health conditions, respectively. Of the 9377 of these infants included in analyses, 256 (2.7%) had a birth defect, 331 (3.5%) were low birth weight, and 596 (6.4%) were born preterm. Among 19,149 infants born to MCS men, 1433 (7.5%) were born to men who screened positive for any mental health condition; 838 (4.4%), 351 (1.8%), and 244 (1.3%) were born to men who screened positive for 1, 2, and 3 mental health conditions, respectively. Of the 18,983 of these infants included in analyses, 54 (2.8%) had a birth defect, 649 (3.4%) were low birth weight, and 1,359 (7.2%) were born preterm. Infants born to men or women who screened positive for all 3 mental health conditions vs. none exhibited elevated risk estimates for each individual infant outcome, but CIs included the null. Increased risk for any adverse infant outcome, however, was observed for women with all 3 mental health conditions (RR = 1.70, CI, 1.12-2.59), but not men (RR = 1.29, CI, 0.89-1.88).

CONCLUSIONS

Findings suggest an association between parental mental health and adverse infant health outcomes, particularly for maternal mental health. Future research would benefit from larger sample sizes to detect potentially small effects of parental mental health on birth outcomes.

Assessing the Impact of Exposure Misclassification in Case-Control Studies of Self-Reported Medication Use

BACKGROUND

Empirically evaluating the potential impact of recall bias on observed associations of prenatal medication exposure is crucial.

OBJECTIVE

We sought to assess the effects of exposure misclassification on previous studies of the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in early pregnancy and increased risk of amniotic band syndrome (ABS).

METHODS

Using data from the National Birth Defects Prevention Study (NBDPS) on births from 1997 to 2011, we included 189 mothers of infants with ABS and 11,829 mothers of infants without congenital anomalies. We identified external studies of medication use during pregnancy to obtain validity parameters for a probabilistic bias analysis to adjust for exposure misclassification. Due to uncertainty about the transportability of these parameters, we conducted multidimensional bias analyses to explore combinations of values on the results.

RESULTS

When we assumed higher specificity in cases or higher sensitivity in controls, misclassification-adjusted estimates suggested confounding-adjusted estimates were attenuated. However, in a few instances, when we assumed greater sensitivity in the cases than the controls (and Sp ≥ 0.9), the misclassification-adjusted estimates suggested upward bias in the confounding-adjusted estimates.

CONCLUSIONS

Results from our bias analysis highlighted that the magnitude of bias depended on the mechanism and the extent of misclassification. However, the parameters available from the validation studies were not directly applicable to our study. In the absence of reliable validation studies, considering mechanisms of bias and simulation studies to outline combinations of plausible scenarios to better inform conclusions on the effects of these medications on pregnancy outcomes remains important.

The Performance of Critical Congenital Heart Disease Screening in Rural Versus Urban Locations in the Northwest United States

Objectives

Pulse oximetry screening of newborns detects critical congenital heart disease (CCHD). Rural birth location is known to affect timing and management of when infants with CHD undergo surgery, but its association with CCHD screening is unknown. We assess the relationship between rural location and postnatal CCHD diagnosis and describe lesion-specific modes of diagnosis.

Study design

Data were abstracted from medical records at 2 cardiac surgery centers in Washington state. Infants with CCHD, defined as CHD requiring either cardiac intervention or resulting in death at <1 month of age, born between July 2015 and June 2020, were included and classified by method of identification. Patient home ZIP codes were used to determine rural location.

Results

We included 561 newborns with CCHD; 35% were diagnosed postnatally. Predominant postnatal mechanisms of identification (n = 194) included symptomatic before CCHD screening period (56%), CCHD screening (22%), and symptomatic after false-negative screen (15%). Postnatal diagnosis rate increased with degree of ruralness (48% in small rural/isolated regions vs 32% in urban regions; P = .01) and incidence of undiagnosed CCHD at birth increased with lower nursery levels (5.5/10 000 live births in nursery level 1 vs 2.1/10 000 live births in level 4).

Conclusions

CCHD screening identifies 22% of postnatally diagnosed CCHD and 7% of cases overall in our region. Postnatal diagnosis is more common in rural regions. The incidence of undiagnosed CCHD at birth increases with decreasing nursery levels. This study supports the value of CCHD screening in routine newborn care, especially in rural areas and hospitals with lower nursery levels.

Bias analyses to investigate the impact of differential participation: Application to a birth defects case-control study

BACKGROUND

Certain associations observed in the National Birth Defects Prevention Study (NBDPS) contrasted with other research or were from areas with mixed findings, including no decrease in odds of spina bifida with periconceptional folic acid supplementation, moderately increased cleft palate odds with ondansetron use and reduced hypospadias odds with maternal smoking.

OBJECTIVES

To investigate the plausibility and extent of differential participation to produce effect estimates observed in NBDPS.

METHODS

We searched the literature for factors related to these exposures and participation and conducted deterministic quantitative bias analyses. We estimated case-control participation and expected exposure prevalence based on internal and external reports, respectively. For the folic acid-spina bifida and ondansetron-cleft palate analyses, we hypothesized the true odds ratio (OR) based on prior studies and quantified the degree of exposure over- (or under-) representation to produce the crude OR (cOR) in NBDPS. For the smoking-hypospadias analysis, we estimated the extent of selection bias needed to nullify the association as well as the maximum potential harmful OR.

RESULTS

Under our assumptions (participation, exposure prevalence, true OR), there was overrepresentation of folic acid use and underrepresentation of ondansetron use and smoking among participants. Folic acid-exposed spina bifida cases would need to have been ≥1.2× more likely to participate than exposed controls to yield the observed null cOR. Ondansetron-exposed cleft palate cases would need to have been 1.6× more likely to participate than exposed controls if the true OR is null. Smoking-exposed hypospadias cases would need to have been ≥1.2 times less likely to participate than exposed controls for the association to falsely appear protective (upper bound of selection bias adjusted smoking-hypospadias OR = 2.02).

CONCLUSIONS

Differential participation could partly explain certain associations observed in NBDPS, but questions remain about why. Potential impacts of other systematic errors (e.g. exposure misclassification) could be informed by additional research.

Lead brownfields and birth defects in North Carolina 2003-2015: A cross-sectional case-control study

BACKGROUND

Brownfields consist of abandoned and disused sites, spanning many former purposes. Brownfields represent a heterogenous yet ubiquitous exposure for many Americans, which may contain hazardous wastes and represent urban blight. Neonates and pregnant individuals are often sensitive to subtle environmental exposures. We evaluate if residential exposure to lead (Pb) brownfields is associated with birth defects.

METHODS

Using North Carolina birth records from 2003 to 2015, we sampled 169,499 births within 10 km of a Pb brownfield with 3255 cardiovascular, central nervous, or external defects identified. Exposure was classified by binary specification of residing within 3 km of a Pb brownfield. We utilized multivariable logistic regression models adjusted for demographic covariates available from birth records and 2010 Census to estimate odds ratios (OR) and 95% confidence intervals (CI). Effect measure modification was assessed by inclusion of interaction terms and stratification for the potential modifiers of race/ethnicity and diabetes status.

RESULTS

We observed positive associations between cardiovascular birth defects and residential proximity to Pb brownfields, OR (95%CI): 1.15 (1.04, 1.26), with suggestive positive associations for central nervous 1.16 (0.91, 1.47) and external defects 1.19 (0.88, 1.59). We did observe evidence of effect measure modification via likelihood ratio tests (LRT) for race/ethnicity for central nervous and external defect groups (LRT p values 0.08 and 0.02). We did observe modification by diabetes status for the cardiovascular group (LRT p value 0.08).

CONCLUSIONS

Our results from this analysis indicate that residential proximity to Pb brownfields is associated with cardiovascular birth defects with suggestive associations for central nervous and external defects. In-depth analyses of individual defects and other contaminants or brownfield site functions may reveal additional novel associations.

Multiple Job Holding, Job Changes, and Associations with Gestational Diabetes and Pregnancy-Related Hypertension in the National Birth Defects Prevention Study

We used National Birth Defects Prevention Study data to investigate associations between working patterns shortly before and during pregnancy and gestational diabetes and pregnancy-related hypertension. We analyzed working patterns (multiple-job holders, job changers, single-job holders) during the three months before and during pregnancy for 8140 participants who delivered a live-born child without a birth defect. "Multiple-job holders" worked more than one job simultaneously, "job changers" worked more than one job with no overlap, and "single-job holders" (referent) worked one job. We used multivariable logistic regression to estimate associations between working pattern and each outcome, adjusting for maternal age and educational attainment at delivery. We explored effect measure modification by household income, peak weekly working hours, and maternal race/ethnicity. Multiple-job holders had higher odds of gestational diabetes (adjusted odds ratio [aOR]: 1.5; 95% confidence interval [CI]: 1.1-2.1) and pregnancy-related hypertension (aOR: 1.5; 95% CI: 1.0-2.2) compared with single-job holders. Multiple-job holders with a household income of more than 30,000 USD per year, 32-44 peak weekly working hours, and from racial/ethnic minority groups had higher odds of gestational diabetes compared with single-job holders in respective categories. Detailed occupational information is important for studies of occupation and maternal health.

The timing, duration, and severity of nausea and vomiting of pregnancy and adverse birth outcomes among controls without birth defects in the National Birth Defects Prevention Study

BACKGROUND

Nausea and vomiting of pregnancy (NVP) occurs in approximately 70% of pregnant people, with varying severity and duration. Treatments include pharmacologic and herbal/natural medications. The associations between NVP and birth outcomes, including preterm birth, small for gestational age (SGA), and low birth weight are inconclusive.

OBJECTIVE

To determine whether NVP and reported medications are associated with adverse birth outcomes.

METHODS

We used data from the population-based, multisite National Birth Defects Prevention Study (1997-2011) to evaluate whether self-reported NVP according to timing, duration, and severity or its specific treatments were associated with preterm birth, SGA, and low birth weight among controls without birth defects. Odds ratios (aOR) and 95% confidence intervals (CI) were adjusted for sociodemographic, reproductive, and medical factors. For any NVP, duration, treatment use, and severity score analyses, the comparison group was participants with no reported NVP. For timing analyses, the comparison group was women with no reported NVP in the same trimester of pregnancy.

RESULTS

Among 6018 participants, 4339 (72.1%) reported any NVP. Among those with NVP, moderate or severe symptoms were more common than mild symptoms. Any versus no NVP was not associated with any of the outcomes of interest. NVP in months 4-6 (aOR 1.21, 95% CI: 1.00, 1.47) and 7-9 (aOR 1.57, 95% CI: 1.22, 2.01) of pregnancy were associated with an increase in the risk of preterm birth. NVP lasting one trimester in duration was associated with decrease in risk of SGA (aOR: 0.74, 95% CI: 0.58, 0.95), and NVP present in every trimester of pregnancy had a 50% increase in risk of preterm birth (aOR: 1.50, 95% CI: 1.11, 2.05). For NVP in months 7-9 and preterm birth, ORs were elevated for moderate (aOR: 1.82, 95% CI: 1.26, 2.63), and severe (aOR: 1.53, 95% CI: 1.06, 2.19) symptoms. NVP was not significantly associated with low birth weight. Our analyses of medications were limited by small numbers, but none suggested increased risk of adverse outcomes associated with use of the medication.

CONCLUSION

Mild NVP and NVP limited to early pregnancy appear to have no effect or a small protective effect on birth outcomes. Long-lasting NVP, severe NVP, and NVP later in pregnancy may increase risk of preterm birth and SGA.

Antifungal medication use during early pregnancy and the risk of congenital heart defects in the National Birth Defects Prevention Study, 1997-2011

BACKGROUND

Fungal infections are common among pregnant people. Recent studies suggest positive associations between oral antifungals used to treat fungal infections and congenital heart defects (CHDs).

METHODS

We estimated associations between first trimester antifungal use and 20 major, specific CHDs using data from the National Birth Defects Prevention Study (NBDPS), a multi-site, case-control study that included pregnancies with estimated delivery dates from October 1997 through December 2011. Infants with CHDs ("cases") were ascertained from 10 birth defect surveillance programs. Live born infants without major birth defects ("controls") were randomly selected from birth records or hospital discharge lists. First trimester antifungal use was self-reported via maternal interview. We estimated adjusted odds ratios (AORs) and 95% confidence intervals (CIs) using logistic regression with Firth's penalized likelihood.

RESULTS

First trimester antifungal use was reported by 148/11,653 (1.3%) case and 123/11,427 (1.1%) control participants. We estimated AORs for 12 CHDs; six had AORs >1.5 (tetralogy of Fallot, double outlet right ventricle with transposition of the great arteries [DORV-TGA], atrioventricular septal defect, hypoplastic left heart syndrome, pulmonary atresia, muscular ventricular septal defect), and one (pulmonary valve stenosis) had an AOR <0.7. All CIs included the null, except for DORV-TGA.

CONCLUSIONS

First trimester antifungal use was rare. We observed some positive associations for several specific CHDs in our analysis, although the CIs largely included the null. Results do not support a large increase in risk, but smaller increases in risk for certain CHD cannot be ruled out.

Nonchromosomal birth defects and risk of childhood acute leukemia: An assessment in 15 000 leukemia cases and 46 000 controls from the Childhood Cancer and Leukemia International Consortium

Although recent studies have demonstrated associations between nonchromosomal birth defects and several pediatric cancers, less is known about their role on childhood leukemia susceptibility. Using data from the Childhood Cancer and Leukemia International Consortium, we evaluated associations between nonchromosomal birth defects and childhood leukemia. Pooling consortium data from 18 questionnaire-based and three registry-based case-control studies across 13 countries, we used multivariable logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between a spectrum of birth defects and leukemia. Our analyses included acute lymphoblastic leukemia (ALL, n = 13 115) and acute myeloid leukemia (AML, n = 2120) cases, along with 46 172 controls. We used the false discovery rate to account for multiple comparisons. In the questionnaire-based studies, the prevalence of birth defects was 5% among cases vs 4% in controls, whereas, in the registry-based studies, the prevalence was 11% among cases vs 7% in controls. In pooled adjusted analyses, there were several notable associations, including (1) digestive system defects and ALL (OR = 2.70, 95% CI: 1.46-4.98); (2) congenital anomalies of the heart and circulatory system and AML (OR = 2.86, 95% CI: 1.81-4.52) and (3) nervous system defects and AML (OR = 4.23, 95% CI: 1.50-11.89). Effect sizes were generally larger in registry-based studies. Overall, our results could point to novel genetic and environmental factors associated with birth defects that could also increase leukemia susceptibility. Additionally, differences between questionnaire- and registry-based studies point to the importance of complementary sources of birth defect phenotype data when exploring these associations.

12-Year Trends of Orofacial Clefts in the United States: Highlighting Racial/Ethnic Differences in Prevalence of Cleft Lip and Cleft Palate

OBJECTIVE

Discrepancies in prevalence among infants with orofacial clefts are public health research priorities. Our objective was to calculate updated estimated prevalence of orofacial clefts in the United States, with sub-analyses by racial/ethnic group.

DESIGN

The National Birth Defect Prevention Network database was used to evaluate trends in cases with orofacial cleft in the United States from 2006 to 2018. Cases with cleft lip with and without cleft palate (CL ± P) and cleft palate (CP) alone were sub-stratified by racial/ethnic category. Estimated prevalence was calculated using the total live births reported in each maternal racial/ethnic group. The odds ratio (OR) was calculated to measure the strength of association between racial/ethnic group and risk of orofacial clefts.

RESULTS

Estimated prevalence rates show that maternally-reported Native American/Alaskan Native individuals were 43.8% (p < 0.0001) and 36.0% (p < 0.0001) more likely to have CL ± P and CP alone, respectively, compared to maternally-reported non-Hispanic White individuals. Estimated prevalence of CL ± P in maternally-reported non-Hispanic Black individuals (OR = 0.64) and maternally-reported Asians/Pacific Islander individuals were significantly lower than in maternally-reported non-Hispanic White individuals (OR = 0.63, p < 0.0001). Estimated prevalence of CP alone was significantly lower in maternally-reported non-Hispanic Black individuals (OR = 0.64, p < 0.0001), maternally-reported Asians/Pacific Islander individuals (OR = 0.69, p < 0.0001), and maternally-reported Hispanic individuals (OR = 0.81, p < 0.0001).

CONCLUSIONS

Across the total population, there was no significant change in estimated orofacial cleft prevalence. However, there were significant disproportions in estimated orofacial cleft prevalence across racial/ethnic groups, which may guide further discussion among craniofacial health care providers and centers and their patients regarding differences in cleft risk factors.

Fever and antibiotic use in maternal urinary tract infections during pregnancy and risk of congenital heart defects: Findings from the National Birth Defects Prevention Study

BACKGROUND

Previous studies report an association between prenatal maternal urinary tract infections (UTI) and specific congenital heart defects (CHDs); however, the role of fever and antibiotic use on this association is poorly understood. Using data from the National Birth Defects Prevention Study, we examined whether the relationship between maternal UTIs during the periconceptional period and occurrence of CHDs is modified by the presence of fever due to UTI and corresponding antibiotic use among 11,704 CHD case infants and 11,636 live-born control infants.

METHODS

Information on UTIs, fever associated with UTI and antibiotic use (sulfonamides, nitrofurantoin, cephalosporins, penicillin, macrolides, and quinolones) during pregnancy were obtained using a computer-assisted telephone interview. Using unconditional multivariable logistic regression, we calculated adjusted odds ratios (ORs) to determine the association between maternal UTIs and subtypes of CHDs. Analyses were stratified by the presence of fever and medication use associated with UTI.

RESULTS

The prevalence of UTIs during the periconceptional period was 7.6% in control mothers, and 8.7% in case mothers. In the absence of fever, UTI was associated with secundum atrial septal defects (ASD) (OR 1.3; 95% confidence interval [CI] 1.1-1.5) and in the absence of antibiotics, UTI was associated with conotruncal defects as a group and for four specific CHDs. When fever and UTI occurred concomitantly, no significantly elevated odds ratios were noticed for any subtypes of CHD. Among women with UTIs who used antibiotics, an elevated but statistically non-significant estimate was observed for secundum ASD (OR 1.4; 95% CI 1.0-2.0).

CONCLUSION

Findings in the present study suggest that fever due to UTI and corresponding maternal antibiotic use do not substantially modify the association between maternal UTIs and specific CHDs in offspring. Further studies with larger sample sizes are warranted to guide clinical management of UTIs during the periconceptional period.

Antifungal medication use during pregnancy and the risk of selected major birth defects in the National Birth Defects Prevention Study, 1997-2011

PURPOSE

Recent studies suggest increased birth defect risk associated with maternal use of specific oral antifungals. We estimated associations between first-trimester antifungal use and selected non-cardiac birth defects using National Birth Defects Prevention Study (NBDPS) data.

METHODS

Participants with a pregnancy affected by a study-eligible birth defect ("cases") were ascertained from 10 birth defect surveillance programs; participants who delivered livebirths without a major birth defect ("controls") were randomly selected from birth records or hospital discharge lists. First-trimester antifungal use was self-reported via maternal interview. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for birth defects with ≥5 exposed cases using logistic regression. We estimated crude ORs and exact 95% CIs for birth defects with 3-4 exposed cases. Additionally, we conducted a probabilistic bias analysis of exposure misclassification.

RESULTS

Our analysis included 19 624 cases and 11 427 controls; 257 (1.3%) cases and 123 (1.1%) controls reported first-trimester antifungal use. Of those who reported antifungals, 62.6% of cases and 64.2% of controls reported topical antifungals; 10.1% of cases and 4.9% of controls reported oral antifungals. We observed the strongest associations for encephalocele and Dandy-Walker malformation and modestly elevated estimates for several other defects. Bias-adjusted estimates were similar to the main analysis.

CONCLUSION

First-trimester antifungal use was positively associated with several birth defects in our analysis, although CIs were imprecise. Further study is warranted to investigate associations between antifungal use and birth defects, including potential bias due to confounding by indication.

A gene-based association test of interactions for maternal-fetal genotypes identifies genes associated with nonsyndromic congenital heart defects

The risk of congenital heart defects (CHDs) may be influenced by maternal genes, fetal genes, and their interactions. Existing methods commonly test the effects of maternal and fetal variants one-at-a-time and may have reduced statistical power to detect genetic variants with low minor allele frequencies. In this article, we propose a gene-based association test of interactions for maternal-fetal genotypes (GATI-MFG) using a case-mother and control-mother design. GATI-MFG can integrate the effects of multiple variants within a gene or genomic region and evaluate the joint effect of maternal and fetal genotypes while allowing for their interactions. In simulation studies, GATI-MFG had improved statistical power over alternative methods, such as the single-variant test and functional data analysis (FDA) under various disease scenarios. We further applied GATI-MFG to a two-phase genome-wide association study of CHDs for the testing of both common variants and rare variants using 947 CHD case mother-infant pairs and 1306 control mother-infant pairs from the National Birth Defects Prevention Study (NBDPS). After Bonferroni adjustment for 23,035 genes, two genes on chromosome 17, TMEM107 (p = 1.64e-06) and CTC1 (p = 2.0e-06), were identified for significant association with CHD in common variants analysis. Gene TMEM107 regulates ciliogenesis and ciliary protein composition and was found to be associated with heterotaxy. Gene CTC1 plays an essential role in protecting telomeres from degradation, which was suggested to be associated with cardiogenesis. Overall, GATI-MFG outperformed the single-variant test and FDA in the simulations, and the results of application to NBDPS samples are consistent with existing literature supporting the association of TMEM107 and CTC1 with CHDs.

Safety surveillance for PrEP in pregnant and breastfeeding women

The risk of HIV acquisition is higher during pregnancy and postpartum than other times. Newly acquired maternal HIV infection associated with high primary viraemia, substantially increases the risk of vertical HIV transmission. Pre-exposure prophylaxis (PrEP) reduces the risk of HIV acquisition. Currently available products include oral tenofovir/emtricitabine (TDF/FTC) and tenofovir alafenamide (TAF)/FTC), long-acting cabotegravir (CAB-LA) and the dapivirine ring (DVR). All except oral TDF/FTC have limited safety data available for use in pregnant and breastfeeding women. The safety of new PrEP agents for pregnant women and the fetus, infant and child, either exposed in utero or during breastfeeding is an ongoing concern for health care workers and pregnant and breastfeeding women, particularly as the safety risk appetite for antiretroviral (ARV) agents used as PrEP is lower in pregnant and breastfeeding women who are HIV-uninfected, compared to women living with HIV taking ARVs as treatment. With the widespread rollout of TDF/FTC among pregnant women in South Africa and other low-middle income countries (LMIC) and the potential introduction of new PrEP agents for pregnant women, there is a need for safety surveillance systems to identify potential signals of risk to either the mother or fetus, measure the burden of such a risk, and where appropriate, provide specific reassurance to PrEP users. Safety data needs to be collected across the continuum of the product life cycle from pre-licensure into the post-marketing period, building a safety profile through both passive and active surveillance systems, recognising the strengths and limitations of each, and the potential for bias and confounding. Pharmacovigilance systems that aim to assess the risk of adverse birth outcomes in pregnant women exposed to PrEP and other agents need to consider the special requirements of pregnancy epidemiology to ensure that the data derived from surveillance are sufficiently robust to inform treatment policies. Here we review the known safety profiles of currently available PrEP candidates in women of child-bearing potential, pregnancy and breastfeeding and discuss pragmatic approaches for such surveillance in HIV-endemic LMICs.

Periconceptional intakes of methyl donors and other micronutrients involved in one-carbon metabolism may further reduce the risk of neural tube defects in offspring: a United States population-based case-control study of women meeting the folic acid recommendations

BACKGROUND

Neural tube defects (NTDs) still occur among some women who consume 400 μg of folic acid for prevention. It has been hypothesized that intakes of methyl donors and other micronutrients involved in one-carbon metabolism may further protect against NTDs.

OBJECTIVES

To investigate whether intakes of vitamin B6, vitamin B12, choline, betaine, methionine, thiamine, riboflavin, and zinc, individually or in combination, were associated with NTD risk reduction in offspring of women meeting the folic acid recommendations.

METHODS

Data were from the National Birth Defects Prevention Study (United States population-based, case-control). We restricted deliveries between 1999 and 2011 with daily periconceptional folic acid supplementation or estimated dietary folate equivalents ≥400 μg. NTD cases were live births, stillbirths, or terminations affected by spina bifida, anencephaly, or encephalocele (n = 1227). Controls were live births without a major birth defect (n = 7095). We categorized intake of each micronutrient as higher or lower based on a combination of diet (estimated from a food frequency questionnaire) and periconceptional vitamin supplementation. We estimated NTD associations for higher compared with lower intake of each micronutrient, individually and in combination, expressed as odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age, race/ethnicity, education, and study center.

RESULTS

NTD associations with each micronutrient were weak to modest. Greater NTD reductions were observed with concurrent higher-amount intakes of multiple micronutrients. For instance, NTD odds were ∼50% lower among participants with ≥4 micronutrients with higher-amount intakes than among participants with ≤1 micronutrient with higher-amount intake (adjusted OR: 0.53; 95% CI: 0.33, 0.86). The strongest reduction occurred with concurrent higher-amount intakes of vitamin B6, vitamin B12, choline, betaine, and methionine (adjusted OR: 0.26; 95% CI: 0.09, 0.77) compared with ≤1 micronutrient with higher-amount intake.

CONCLUSIONS

Our findings support that NTD prevention, in the context of folic acid fortification, could be augmented with intakes of methyl donors and other micronutrients involved in folate metabolism.

Oxidative balance scores and neural crest cell-related congenital anomalies

Oxidative stress and redox imbalance adversely affect embryonic development. We developed two oxidative balance scores (OBS) that include dietary and nondietary exposures. We hypothesized that higher scores (i.e., lower oxidative stress) would be associated with lower risk of neural tube defects, orofacial clefts, conotruncal heart defects, and limb deficiencies. We used data from the National Birth Defects Prevention Study to create a dietary OBS based on intake of 13 nutrients and an overall OBS that included the 13 nutrients and eight additional nondietary factors related to oxidative balance (e.g., smoking). We used logistic regression to examine odds ratios associated with having low or high scores (i.e., <10th or >90th percentiles). Continuous models indicated reduced odds associated with high versus low scores (i.e., comparing odds at the 90th versus 10th percentile values of the distribution) on the overall OBS for cleft lip with or without cleft palate [adjusted odds ratio (aOR) 0.72, 95% confidence interval (CI) 0.63-0.82], longitudinal limb deficiency (aOR 0.73, CI 0.54-0.99), and transverse limb deficiency (aOR 0.74, CI 0.58-0.95); increased odds for anencephaly (aOR 1.40, CI 1.07-1.84); and primarily nonsignificant associations with conotruncal heart defects. Results for the dietary OBS were similar. This study provides some evidence that oxidative stress contributes to congenital anomalies related to neural crest cell development.

Exome-wide assessment of isolated biliary atresia: A report from the National Birth Defects Prevention Study using child-parent trios and a case-control design to identify novel rare variants

The etiology of biliary atresia (BA) is unknown, but recent studies suggest a role for rare protein-altering variants (PAVs). Exome sequencing data from the National Birth Defects Prevention Study on 54 child-parent trios, one child-mother duo, and 1513 parents of children with other birth defects were analyzed. Most (91%) cases were isolated BA. We performed (1) a trio-based analysis to identify rare de novo, homozygous, and compound heterozygous PAVs and (2) a case-control analysis using a sequence kernel-based association test to identify genes enriched with rare PAVs. While we replicated previous findings on PKD1L1, our results do not suggest that recurrent de novo PAVs play important roles in BA susceptibility. In fact, our finding in NOTCH2, a disease gene associated with Alagille syndrome, highlights the difficulty in BA diagnosis. Notably, IFRD2 has been implicated in other gastrointestinal conditions and warrants additional study. Overall, our findings strengthen the hypothesis that the etiology of BA is complex.

Maternal dietary caffeine consumption and risk of birth defects in the National Birth Defects Prevention Study, 1997-2011

BACKGROUND

Caffeine consumption is common during pregnancy, but published associations with birth defects are mixed. We updated estimates of associations between prepregnancy caffeine consumption and 48 specific birth defects from the National Birth Defects Prevention Study (NBDPS) for deliveries from 1997 to 2011.

METHODS

NBDPS was a large population-based case-control study conducted in 10 U.S. states. We categorized self-reported total dietary caffeine consumption (mg/day) from coffee, tea, soda, and chocolate as: <10, 10 to <100, 100 to <200, 200 to <300, and ≥ 300. We used logistic regression to estimate adjusted odds ratios (aORs [95% confidence intervals]). Analyses for defects with ≥5 exposed case children were adjusted for maternal race/ethnicity, age at delivery, body mass index, early pregnancy cigarette smoking and alcohol use, and study site.

RESULTS

Our analysis included 30,285 case and 11,502 control children, with mothers of 52% and 54%, respectively, reporting consuming <100 mg caffeine, and 11% of mothers of both cases and controls reported consuming ≥300 mg per day. Low (10 to <100 mg/day) levels of prepregnancy caffeine consumption were associated with statistically significant increases in aORs (1.2-1.7) for 10 defects. Associations with high (≥300 mg/day) levels of caffeine were generally weaker, except for craniosynostosis and aortic stenosis (aORs = 1.3 [1.1-1.6], 1.6 [1.1-2.3]).

CONCLUSIONS

Given the large number of estimates generated, some of the statistically significant results may be due to chance and thus the weakly increased aORs should be interpreted cautiously. This study supports previous observations suggesting lack of evidence for meaningful associations between caffeine consumption and the studied birth defects.

The association of nausea and vomiting of pregnancy, its treatments, and select birth defects: Findings from the National Birth Defect Prevention Study

BACKGROUND

Nausea and vomiting of pregnancy (NVP) occurs in approximately 70% of pregnant people. Treatments include pharmacologic and herbal/natural products. Research on the associations between NVP and its treatments and birth defects is limited.

METHODS

We used data from the case-control National Birth Defects Prevention Study (1997-2011) to examine whether first-trimester NVP or its specific treatments were associated with 37 major birth defects. Odds ratios (aOR) and 95% confidence intervals (CIs) were adjusted for sociodemographic and reproductive factors.

RESULTS

Mothers of 66.6% of 28,628 cases and 69.9% of 11,083 controls reported first-trimester NVP. Compared to no NVP, mothers with NVP had ≥10% reduction in risk of cardiac and noncardiac defects overall, and of 18 specific defects. Over-the-counter antiemetic use, compared to untreated NVP, was associated with ≥10% increase in risk for nine defect groups (heterotaxy, hypoplastic left heart syndrome [HLHS], aortic stenosis, cataracts, anophthalmos/microphthalmos, biliary atresia, transverse limb deficiency, omphalocele, and gastroschisis), whereas use of prescription antiemetics increased risk ≥10% for seven defect groups (tetralogy of Fallot, HLHS, spina bifida, anopthlamos/microphthalmos, cleft palate, craniosynostosis, and diaphragmatic hernia). We observed increased risks for promethazine and tetralogy of Fallot (aOR: 1.49, 95% CI: 1.05-2.10), promethazine and craniosynostosis (1.44, 1.08-1.92), ondansetron and cleft palate (1.66, 1.18-2.31), pyridoxine and heterotaxy (3.91, 1.49-10.27), and pyridoxine and cataracts (2.57, 1.12-5.88).

CONCLUSIONS

NVP does not increase risks of birth defects. Our findings that some treatments for NVP increase risk of specific birth defects should be investigated further before clinical recommendations are made.

Early pregnancy vitamin D status and risk of select congenital anomalies in the National Birth Defects Prevention Study

INTRODUCTION

Vitamin D deficiency is associated with adverse pregnancy events. However, its role in the etiology of congenital anomalies remains unclear. We examined the association between vitamin D status, measured through prepregnancy diet, UV exposure, season of conception, and congenital anomalies.

METHODS

We used data from the National Birth Defects Prevention Study, a U.S. population-based case-control study (1997-2011). Prepregnancy dietary vitamin D was calculated from food frequency questionnaires and evaluated using tertiles, based on the distribution in controls. We used the National Oceanic and Atmospheric Administration Weather Service to assign UV indices based on location and estimated date of conception, then dichotomized UV exposure (low vs. high). Seasons of conception was categorized as fall/winter spring/summer. We used logistic regression to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI).

RESULTS

Lower prepregnancy dietary vitamin D intake (<65.21 IU/d vs. >107.55 IU/d) was associated with increased odds of anencephaly (aOR = 1.28, 95% CI 1.01, 1.63), hypospadias (aOR = 1.21, 95% CI 1.04, 1.40), septal defects (aOR = 1.16, 95% CI 1.05, 1.30), diaphragmatic hernia (aOR = 1.42, 95% CI 1.13, 1.79), and gastroschisis (aOR = 1.27, 95% CI 1.07, 1.52). Findings were consistent when we stratified by UV exposure and season of conception.

CONCLUSIONS

Our findings suggest lower dietary intake of vitamin D may be associated with increased risk of select congenital anomalies. Further investigations are warranted to evaluate the effects of other nutrients and appropriate thresholds and sources of vitamin D using serum.

Gene-Folic Acid Interactions and Risk of Conotruncal Heart Defects: Results from the National Birth Defects Prevention Study

Conotruncal heart defects (CTDs) are heart malformations that affect the cardiac outflow tract and typically cause significant morbidity and mortality. Evidence from epidemiological studies suggests that maternal folate intake is associated with a reduced risk of heart defects, including CTD. However, it is unclear if folate-related gene variants and maternal folate intake have an interactive effect on the risk of CTDs. In this study, we performed targeted sequencing of folate-related genes on DNA from 436 case families with CTDs who are enrolled in the National Birth Defects Prevention Study and then tested for common and rare variants associated with CTD. We identified risk alleles in maternal MTHFS (OR_meta = 1.34; 95% CI 1.07 to 1.67), maternal NOS2 (OR_meta = 1.34; 95% CI 1.05 to 1.72), fetal MTHFS (OR_meta = 1.35; 95% CI 1.09 to 1.66), and fetal TCN2 (OR_meta = 1.38; 95% CI 1.12 to 1.70) that are associated with an increased risk of CTD among cases without folic acid supplementation. We detected putative de novo mutations in genes from the folate, homocysteine, and transsulfuration pathways and identified a significant association between rare variants in MGST1 and CTD risk. Results suggest that periconceptional folic acid supplementation is associated with decreased risk of CTD among individuals with susceptible genotypes.

Birth defects associated with paternal firefighting in the National Birth Defects Prevention Study

BACKGROUND

Few studies have evaluated birth defects among children of firefighters. We investigated associations between birth defects and paternal work as a firefighter compared to work in non-firefighting and police officer occupations.

METHODS

We analyzed 1997-2011 data from the multi-site case-control National Birth Defects Prevention Study. Cases included fetuses or infants with major structural birth defects and controls included a random sample of live-born infants without major birth defects. Mothers of infants self-reported information about parents' occupations held during pregnancy. We investigated associations between paternal firefighting and birth defect groups using logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Referent groups included families reporting fathers working non-firefighting and police officer jobs.

RESULTS

Occupational groups included 227 firefighters, 36,285 non-firefighters, and 433 police officers. Twenty-nine birth defects were analyzed. In adjusted analyses, fathers of children with total anomalous pulmonary venous return (TAPVR; OR = 3.1; 95% CI = 1.1-8.7), cleft palate (OR = 1.8; 95% CI = 1.0-3.3), cleft lip (OR = 2.2; 95% CI = 1.2-4.2), and transverse limb deficiency (OR = 2.2; 95% CI = 1.1-4.7) were more likely than fathers of controls to be firefighters, versus non-firefighters. In police-referent analyses, fathers of children with cleft palate were 2.4 times more likely to be firefighters than fathers of controls (95% CI = 1.1-5.4).

CONCLUSIONS

Paternal firefighting may be associated with an elevated risk of birth defects in offspring. Additional studies are warranted to replicate these findings. Further research may contribute to a greater understanding of the reproductive health of firefighters and their families for guiding workplace practices.

A genome-wide association study of obstructive heart defects among participants in the National Birth Defects Prevention Study

Obstructive heart defects (OHDs) share common structural lesions in arteries and cardiac valves, accounting for ~25% of all congenital heart defects. OHDs are highly heritable, resulting from interplay among maternal exposures, genetic susceptibilities, and epigenetic phenomena. A genome-wide association study was conducted in National Birth Defects Prevention Study participants (Ndiscovery  = 3978; Nreplication  = 2507), investigating the genetic architecture of OHDs using transmission/disequilibrium tests (TDT) in complete case-parental trios (Ndiscovery_TDT  = 440; Nreplication_TDT  = 275) and case-control analyses separately in infants (Ndiscovery_CCI  = 1635; Nreplication_CCI  = 990) and mothers (case status defined by infant; Ndiscovery_CCM  = 1703; Nreplication_CCM  = 1078). In the TDT analysis, the SLC44A2 single nucleotide polymorphism (SNP) rs2360743 was significantly associated with OHD (pdiscovery  = 4.08 × 10-9 ; preplication  = 2.44 × 10-4 ). A CAPN11 SNP (rs55877192) was suggestively associated with OHD (pdiscovery  = 1.61 × 10-7 ; preplication  = 0.0016). Two other SNPs were suggestively associated (p < 1 × 10-6 ) with OHD in only the discovery sample. In the case-control analyses, no SNPs were genome-wide significant, and, even with relaxed thresholds ( × discovery  < 1 × 10-5 and preplication  < 0.05), only one SNP (rs188255766) in the infant analysis was associated with OHDs (pdiscovery  = 1.42 × 10-6 ; preplication  = 0.04). Additional SNPs with pdiscovery  < 1 × 10-5 were in loci supporting previous findings but did not replicate. Overall, there was modest evidence of an association between rs2360743 and rs55877192 and OHD and some evidence validating previously published findings.

Maternal hereditary hemolytic anemia and birth defects in the National Birth Defects Prevention Study

OBJECTIVES

Hereditary hemolytic anemia (HHA) results from genetic mutations that cause red blood cell abnormalities. Little research exists on the relationship between HHA and birth defects. Using data from the National Birth Defects Prevention Study (NBDPS), we described characteristics of HHA-exposed women and estimated associations between HHA during pregnancy and specific birth defects.

METHODS

The NBDPS was a population-based, case-control study of major birth defects and included pregnancies with estimated delivery dates from October 1997 through December 2011. Participants were ascertained from hospital discharge lists or birth defect registries at 10 sites. Trained interviewers collected information about pregnancy exposures via telephone questionnaire. We described characteristics among HHA-exposed women and calculated crude odds ratios and exact 95% confidence intervals for defects with ≥3 exposed cases.

RESULTS

Among 31 HHA-exposed women (28 cases/3 controls), 13 (42%) reported sickle cell anemia, 17 (55%) reported thalassemia, and one (3%) reported hereditary spherocytosis. The average age at delivery for HHA-exposed case women was 27.3 years (range: 17-38). The majority (82%) of HHA-exposed case women reported additional conditions during pregnancy, including hypertension, genitourinary infections, and respiratory illnesses. Additionally, 93% of case women reported using medication during pregnancy. Among the 28 cases, 18 (64%) had isolated birth defects. The defects with ≥3 exposed cases were anencephaly, atrial septal defect, gastroschisis, and cleft palate. Except for anencephaly, the 95% confidence intervals for all estimates were close to or included the null.

CONCLUSION

This hypothesis-generating study adds to the sparse literature on the association between HHA and birth defects.

A cross-sectional study of brownfields and birth defects

BACKGROUND

Brownfields are a multitude of abandoned and disused sites, spanning many former purposes. Brownfields represent a heterogenous yet ubiquitous exposure for many Americans, which may contain hazardous wastes and represent urban blight. Neonates and pregnant individuals are often sensitive to subtle environmental exposures. We evaluate whether residential brownfield exposure is associated with birth defects.

METHODS

Using North Carolina birth records from 2003 to 2015, we sampled 753,195 births with 39,495 defects identified. We examined defect groups and 30 distinct phenotypes. Number of brownfields within 2,000 m of the residential address at birth was summed. We utilized mixed effects multivariable logistic regression models adjusted for demographic and environmental covariates available from birth records, 2010 Census, and EPA's Environmental Quality Index to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

We observed positive associations between cardiovascular and external defect groups (OR [95% CI]: 1.07 [1.02-1.13] and 1.17 [1.01-1.35], respectively) and any brownfield exposure. We also observed positive associations with atrial septal and ventricular septal defects (1.08 [1.01-1.16] and 1.15 [1.03-1.28], respectively), congenital cataracts (1.38 [0.98-1.96]), and an inverse association with gastroschisis (0.74 [0.58-0.94]). Effect estimates for several additional defects were positive, though we observed null associations for most group and individual defects. Additional analyses indicated an exposure-response relationship for several defects across levels of brownfield exposure.

CONCLUSIONS

Our results indicate that residential proximity to brownfields is associated with birth defects, especially cardiovascular and external defects. In-depth analyses of individual defects and specific contaminants or brownfield sites may reveal additional novel associations.

Maternal occupation as a nail technician or hairdresser during pregnancy and birth defects, National Birth Defects Prevention Study, 1997-2011

OBJECTIVE

Nail technicians and hairdressers may be exposed to chemicals with potential reproductive effects. While studies have examined birth defects in children of hairdressers, those in children of nail technicians have not been evaluated. We investigated associations between selected birth defects and maternal occupation as a nail technician or hairdresser versus a non-cosmetology occupation during pregnancy.

METHODS

We analysed population-based case-control data from the multisite National Birth Defects Prevention Study, 1997-2011. Cases were fetuses or infants with major structural birth defects; controls were live-born infants without major birth defects. Expert raters classified self-reported maternal jobs as nail technician, combination nail technician-hairdresser, hairdresser, other cosmetology work or non-cosmetology work. We used logistic regression to calculate adjusted ORs and 95% CIs for associations between occupation during pregnancy and birth defects, controlling for age, smoking, education and race/ethnicity.

RESULTS

Sixty-one mothers worked as nail technicians, 196 as hairdressers, 39 as combination nail technician-hairdressers and 42 810 as non-cosmetologists. The strongest associations among nail technicians included seven congenital heart defect (CHD) groups (ORs ranging from 2.7 to 3.5) and neural tube defects (OR=2.6, CI=0.8 to 8.4). Birth defects most strongly associated with hairdressing included anotia/microtia (OR=2.1, CI=0.6 to 6.9) and cleft lip with cleft palate (OR=2.0, CI=1.1 to 3.7). All oral cleft groups were associated with combination nail technician-hairdresser work (ORs ranging from 4.2 to 5.3).

CONCLUSIONS

Small samples resulted in wide CIs. Still, results suggest associations between maternal nail technician work during pregnancy and CHDs and between hairdressing work and oral clefts.

Proportion of critical congenital heart defects attributable to unhealthy prepregnancy body mass index among women with live births in Florida, 2005-2016

BACKGROUND

Associations between maternal prepregnancy body mass index (BMI) and congenital heart defects have been reported, however, the proportion of critical congenital heart defects (CCHDs) attributable to unhealthy prepregnancy BMI has not been determined. Our objective was to investigate the association between maternal prepregnancy BMI and CCHDs.

METHODS

The Florida Birth Defects Registry was used to identify infants with CCHDs born between 2005-2016. Birth certificate data were used to define the source population and identify perinatal and socio-demographic characteristics. BMI values were categorized as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), obese I (30.0-34.9), obese II (35.0-39.9), and obese III (≥40.0). Multi-predictor logistic regression models were used to estimate adjusted odds ratios (aORs) and 99% confidence intervals representing the association between maternal prepregnancy BMI and CCHDs. Adjusted population attributable fractions (PAFs) for the aORs were calculated.

RESULTS

We observed a significantly increased risk of "any CCHD" in infants born to women at any level of obesity. Among the 12 CCHDs examined, 5 showed a significantly increased risk among mothers in the two highest obesity levels (II & III). Approximately 8% of all CCHDs may be attributed to suboptimal maternal prepregnancy BMI, with the highest total individual CCHD PAFs for pulmonary valve atresia (21.7%) and total anomalous pulmonary venous return (12.8%).

CONCLUSIONS

Women with suboptimal prepregnancy BMI are at increased odds of having a child born with a CCHD. We found evidence of a direct dose-response relationship between prepregnancy BMI and odds for CCHD; with variation by CCHD subtype.

Testing and Validating Semi-automated Approaches to the Occupational Exposure Assessment of Polycyclic Aromatic Hydrocarbons

INTRODUCTION

When it is not possible to capture direct measures of occupational exposure or conduct biomonitoring, retrospective exposure assessment methods are often used. Among the common retrospective assessment methods, assigning exposure estimates by multiple expert rater review of detailed job descriptions is typically the most valid, but also the most time-consuming and expensive. Development of screening protocols to prioritize a subset of jobs for expert rater review can reduce the exposure assessment cost and time requirement, but there is often little data with which to evaluate different screening approaches. We used existing job-by-job exposure assessment data (assigned by consensus between multiple expert raters) from a large, population-based study of women to create and test screening algorithms for polycyclic aromatic hydrocarbons (PAHs) that would be suitable for use in other population-based studies.

METHODS

We evaluated three approaches to creating a screening algorithm: a machine-learning algorithm, a set of a priori decision rules created by experts based on features (such as keywords) found in the job description, and a hybrid algorithm incorporating both sets of criteria. All coded jobs held by mothers of infants participating in National Birth Defects Prevention Study (NBDPS) (n = 35,424) were used in developing or testing the screening algorithms. The job narrative fields considered for all approaches included job title, type of product made by the company, main activities or duties, and chemicals or substances handled. Each screening approach was evaluated against the consensus rating of two or more expert raters.

RESULTS

The machine-learning algorithm considered over 30,000 keywords and industry/occupation codes (separate and in combination). Overall, the hybrid method had a similar sensitivity (87.1%) as the expert decision rules (85.5%) but was higher than the machine-learning algorithm (67.7%). Specificity was best in the machine-learning algorithm (98.1%), compared to the expert decision rules (89.2%) and hybrid approach (89.1%). Using different probability cutoffs in the hybrid approach resulted in improvements in sensitivity (24-30%), without the loss of much specificity (7-18%).

CONCLUSION

Both expert decision rules and the machine-learning algorithm performed reasonably well in identifying the majority of jobs with potential exposure to PAHs. The hybrid screening approach demonstrated that by reviewing approximately 20% of the total jobs, it could identify 87% of all jobs exposed to PAHs; sensitivity could be further increased, albeit with a decrease in specificity, by adjusting the algorithm. The resulting screening algorithm could be applied to other population-based studies of women. The process of developing the algorithm also provides a useful illustration of the strengths and potential pitfalls of these approaches to developing exposure assessment algorithms.

Short interpregnancy intervals and risks for birth defects: support for the nutritional depletion hypothesis

BACKGROUND

Research suggests short interpregnancy intervals increase risks for adverse perinatal outcomes, including some birth defects. A hypothesized cause is nutritional depletion, including folic acid (FA).

OBJECTIVES

We evaluated associations between short interpregnancy intervals, alone and in combination with FA intake, and the occurrence of select malformations.

METHODS

Data were from the National Birth Defects Prevention Study (US case-control, 1997-2011). Participants included multiparous women whose prior pregnancy resulted in live birth. Cases included 8 noncardiac and 6 cardiac defect groups (n = 3219); controls were nonmalformed live-borns (n = 2508). We categorized interpregnancy interval (<6, 6-11, 12-17, and 18-23 mo) and periconceptional FA intake [no FA supplement use and dietary folate equivalents (DFE) <400 µg/d, no FA supplement use and DFE ≥400 µg/d, or any FA supplement use]. We controlled for age, race/ethnicity, income, pregnancy intention, and study center. ORs <0.8 or >1.2 were considered to represent potentially meaningful associations.

RESULTS

ORs for <6 compared with 18-23 mo were >1.2 for 4/8 noncardiac and 3/6 cardiac malformations. Among participants with any FA supplement use, ORs comparing <6 with 6-23 mo were <1.2 for most defects. Conversely, most ORs were >1.2 for <6 mo + no FA supplement use and DFE <400 µg/d compared with 6-23 mo + any FA supplement use. Magnitude and precision varied by defect.

CONCLUSIONS

Short interpregnancy intervals were associated with a trend of higher risks for several defects, notably in the absence of FA supplement use. To our knowledge, our study is the first to provide preliminary empirical support that these etiologies may be related to shorter interpregnancy intervals and possible nutritional deficiencies. Because FA intake is highly correlated with other nutrients, and because our estimates were generally imprecise, more research with larger sample sizes is needed to better understand the role of FA compared with other nutrients in each defect-specific etiology.

Congenital Heart Disease and Myelomeningocele in the Newborn: Prevalence and Mortality

Myelomeningocele (MMC) and congenital heart disease (CHD) are independent risk factors for increased morbidity and mortality in the newborn period and each can require significant operations shortly after birth. Few studies have examined the impact of these combined lesions. We sought to examine the incidence of CHD in patients with MMC, and to evaluate length of stay (LOS), hospital charges, and mortality. Using the Texas Inpatient Public Use Data File, ~ 6.9 million newborn records between 1/1999 and 12/2016 were examined. Hospitalizations were classified as MMC without CHD (n = 3054), CHD without MMC (n = 72,266), and MMC with CHD (n = 171). The birth prevalence of CHD with MMC was 0.3/10,000 live hospital births, with 5% of patients with MMC having CHD, and 0.2% of those with CHD having MMC. There was increased LOS in patients with both MMC and CHD (median 15 days, IQR 5-31), compared to CHD without MMC (median 6 days, IQR 2-20) and MMC without CHD (median 8 days, IQR 1-14) and higher total hospital charges (median $95,007, IQR $26,731-$222,660) compared to CHD without MMC (median $27,726, $6463-$118,370) and MMC without CHD (median $40,066, IQR $5744-$97,490). Mortality was significantly higher in patients with MMC and CHD (22.2% compared to 3.1% in MMC without CHD and 4.1% in CHD without MMC). Significance remained when limiting for patients without genetic conditions or additional major birth defects. MMC with CHD in the newborn compared to either CHD or MMC alone is associated with longer LOS, higher charges, and increased mortality.

Gene-environment interactions between air pollution and biotransformation enzymes and risk of birth defects

Genetic and environmental factors have been observed to influence risks for birth defects, though few studies have investigated gene-environment interactions. Our aim was to examine the interaction terms of gene variants in biotransformation enzyme pathways and air pollution exposures in relation to risk of several structural birth defects. We evaluated the role of ambient air pollutant exposure (nitrogen dioxide [NO2 ], nitrogen oxide, carbon monoxide, particulate matter <10 [PM10 ] and <2.5 [PM2.5 ] microns) during pregnancy and 104 gene variants of biotransformation enzymes from infant bloodspots or buccal cells in a California population-based case-control study in 1997-2006. Cases included cleft lip with or without cleft palate (N = 206), gastroschisis (N = 94), tetralogy of Fallot (N = 69), and dextro-transposition of the great arteries (d-TGA; N = 40) and were compared to 208 nonmalformed controls. Overall, the results were not consistent, though did highlight some associations for further investigation as indicated by Wald chi-square test p value <.1. Increased risk of cleft lip was associated with exposure to high PM10 and two CYP gene variants. High PM2.5 and the variant of SLCO1B1 was associated with increased risk of teratology of Fallot. Higher NO2 and two gene variants, CYP2A6 and SLC01B1, were associated with increased risk of d-TGA. Results for gastroschisis were inconsistent in direction and across pollutants. These exploratory results suggest that some individuals based on their genetic background may be more susceptible to the adverse effects of air pollution.

The safety of asthma medications during pregnancy and lactation: Clinical management and research priorities

Asthma is one of the most common underlying diseases in women of reproductive age that can lead to potentially serious medical problems during pregnancy and lactation. A group of key stakeholders across multiple relevant disciplines was invited to take part in an effort to prioritize, strategize, and mobilize action steps to fill important gaps in knowledge regarding asthma medication safety in pregnancy and lactation. The stakeholders identified substantial gaps in the literature on the safety of asthma medications used during pregnancy and lactation and prioritized strategies to fill those gaps. Short-term action steps included linking data from existing complementary study designs (US and international claims data, single drug pregnancy registries, case-control studies, and coordinated systematic data systems). Long-term action steps included creating an asthma disease registry, incorporating the disease registry into electronic health record systems, and coordinating care across disciplines. The stakeholders also prioritized establishing new infrastructures/collaborations to perform research in pregnant and lactating women and to include patient perspectives throughout the process. To address the evidence gaps, and aid in populating product labels with data that inform clinical decision making, the consortium developed a plan to systematically obtain necessary data in the most efficient and timely manner.

Paternal genetic variants and risk of obstructive heart defects: A parent-of-origin approach

Previous research on risk factors for obstructive heart defects (OHDs) focused on maternal and infant genetic variants, prenatal environmental exposures, and their potential interaction effects. Less is known about the role of paternal genetic variants or environmental exposures and risk of OHDs. We examined parent-of-origin effects in transmission of alleles in the folate, homocysteine, or transsulfuration pathway genes on OHD occurrence in offspring. We used data on 569 families of liveborn infants with OHDs born between October 1997 and August 2008 from the National Birth Defects Prevention Study to conduct a family-based case-only study. Maternal, paternal, and infant DNA were genotyped using an Illumina Golden Gate custom single nucleotide polymorphism (SNP) panel. Relative risks (RR), 95% confidence interval (CI), and likelihood ratio tests from log-linear models were used to estimate the parent-of-origin effect of 877 SNPs in 60 candidate genes in the folate, homocysteine, and transsulfuration pathways on the risk of OHDs. Bonferroni correction was applied for multiple testing. We identified 3 SNPs in the transsulfuration pathway and 1 SNP in the folate pathway that were statistically significant after Bonferroni correction. Among infants who inherited paternally-derived copies of the G allele for rs6812588 in the RFC1 gene, the G allele for rs1762430 in the MGMT gene, and the A allele for rs9296695 and rs4712023 in the GSTA3 gene, RRs for OHD were 0.11 (95% CI: 0.04, 0.29, P = 9.16x10-7), 0.30 (95% CI: 0.17, 0.53, P = 9.80x10-6), 0.34 (95% CI: 0.20, 0.57, P = 2.28x10-5), and 0.34 (95% CI: 0.20, 0.58, P = 3.77x10-5), respectively, compared to infants who inherited maternally-derived copies of the same alleles. We observed statistically significant decreased risk of OHDs among infants who inherited paternal gene variants involved in folate and transsulfuration pathways.

Centered Partition Processes: Informative Priors for Clustering (with Discussion)

There is a very rich literature proposing Bayesian approaches for clustering starting with a prior probability distribution on partitions. Most approaches assume exchangeability, leading to simple representations in terms of Exchangeable Partition Probability Functions (EPPF). Gibbs-type priors encompass a broad class of such cases, including Dirichlet and Pitman-Yor processes. Even though there have been some proposals to relax the exchangeability assumption, allowing covariate-dependence and partial exchangeability, limited consideration has been given on how to include concrete prior knowledge on the partition. For example, we are motivated by an epidemiological application, in which we wish to cluster birth defects into groups and we have prior knowledge of an initial clustering provided by experts. As a general approach for including such prior knowledge, we propose a Centered Partition (CP) process that modifies the EPPF to favor partitions close to an initial one. Some properties of the CP prior are described, a general algorithm for posterior computation is developed, and we illustrate the methodology through simulation examples and an application to the motivating epidemiology study of birth defects.

Innovative approach to identify multigenomic and environmental interactions associated with birth defects in family-based hybrid designs

Genes, including those with transgenerational effects, work in concert with behavioral, environmental, and social factors via complex biological networks to determine human health. Understanding complex relationships between causal factors underlying human health is an essential step towards deciphering biological mechanisms. We propose a new analytical framework to investigate the interactions between maternal and offspring genetic variants or their surrogate single nucleotide polymorphisms (SNPs) and environmental factors using family-based hybrid study design. The proposed approach can analyze diverse genetic and environmental factors and accommodate samples from a variety of family units, including case/control-parental triads, and case/control-parental dyads, while minimizing potential bias introduced by population admixture. Comprehensive simulations demonstrated that our innovative approach outperformed the log-linear approach, the best available method for case-control family data. The proposed approach had greater statistical power and was capable to unbiasedly estimate the maternal and child genetic effects and the effects of environmental factors, while controlling the Type I error rate against population stratification. Using our newly developed approach, we analyzed the associations between maternal and fetal SNPs and obstructive and conotruncal heart defects, with adjustment for demographic and lifestyle factors and dietary supplements. Fourteen and 11 fetal SNPs were associated with obstructive and conotruncal heart defects, respectively. Twenty-seven and 17 maternal SNPs were associated with obstructive and conotruncal heart defects, respectively. In addition, maternal body mass index was a significant risk factor for obstructive defects. The proposed approach is a powerful tool for interrogating the etiological mechanism underlying complex traits.

Maternal Hypertension-Related Genotypes and Congenital Heart Defects

BACKGROUND

Maternal hypertension has been associated with congenital heart defect occurrence in several studies. We assessed whether maternal genotypes associated with this condition were also associated with congenital heart defect occurrence.

METHODS

We used data from the National Birth Defects Prevention Study to identify non-Hispanic white (NHW) and Hispanic women with (cases) and without (controls) a pregnancy in which a select simple, isolated heart defect was present between 1999 and 2011. We genotyped 29 hypertension-related single nucleotide polymorphisms (SNPs). We conducted logistic regression analyses separately by race/ethnicity to assess the relationship between the presence of any congenital heart defect and each SNP and an overall blood pressure genetic risk score (GRS). All analyses were then repeated to assess 4 separate congenital heart defect subtypes.

RESULTS

Four hypertension-related variants were associated with congenital heart defects among NHW women (N = 1,568 with affected pregnancies). For example, 1 intronic variant in ARHGAP2, rs633185, was associated with conotruncal defects (odds ratio [OR]: 1.3, 95% confidence interval [CI]: 1.1-1.6). Additionally, 2 variants were associated with congenital heart defects among Hispanic women (N = 489 with affected pregnancies). The GRS had a significant association with septal defects (OR: 2.1, 95% CI: 1.2-3.5) among NHW women.

CONCLUSIONS

We replicated a previously reported association between rs633185 and conotruncal defects. Although additional hypertension-related SNPs were also associated with congenital heart defects, more work is needed to better understand the relationship between genetic risk for maternal hypertension and congenital heart defects occurrence.

Male Sex and the Risk of Childhood Cancer: The Mediating Effect of Birth Defects

Background

There is a persistent, unexplained disparity in sex ratio among childhood cancer cases, whereby males are more likely to develop most cancers. This male predominance is also seen for most birth defects, which are strongly associated with risk of childhood cancer. We conducted mediation analysis to estimate whether the increased risk of cancer among males is partially explained by birth defect status.

Methods

We used a population-based birth cohort with linked data from birth certificates, birth defects registries, and cancer registries from Arkansas, Michigan, North Carolina, and Texas. We conducted counterfactual mediation analysis to estimate the natural direct and indirect effects of sex on cancer risk, modeling birth defect status as mediator. State; birth year; plurality; and maternal race and ethnicity, age, and education were considered confounders. We conducted separate analyses limited to cancers diagnosed younger than 1 year of age.

Results

Our dataset included 10 181 074 children: 15 110 diagnosed with cancer, 539 567 diagnosed with birth defects, and 2124 co-occurring cases. Birth defect status mediated 38% of the association between sex and cancer overall. The proportion mediated varied by cancer type, including acute myeloid leukemia (93%), neuroblastoma (35%), and non-Hodgkin lymphoma (6%). Among children younger than 1 year of age at cancer diagnosis, the proportion mediated was substantially higher (82%).

Conclusions

Our results suggest that birth defects mediate a statistically significant proportion of the relationship between sex and childhood cancer. The proportion mediated varied by cancer type and diagnosis age. These findings improve our understanding of the causal pathway underlying male sex as a risk factor for childhood cancer.

Use of antihistamine medications during early pregnancy and selected birth defects: The National Birth Defects Prevention Study, 1997-2011

BACKGROUND

It is estimated that approximately 10-15% of pregnant women report antihistamine use during pregnancy. Although antihistamines are generally considered safe during pregnancy, results from published studies are inconsistent.

METHODS

Using a case-control study design we analyzed 41,148 pregnancies (30,091 cases and 11,057 controls) from the National Birth Defects Prevention Study (1997-2011). Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals for 64 birth defect groupings in relation to early pregnancy exposure to 14 distinct antihistamines. Models were adjusted for maternal age, race, parity, education level, prenatal care, folic acid use, smoking and alcohol use, and study site.

RESULTS

Approximately 13% of cases and controls were exposed to an antihistamine during early pregnancy. Analyses were restricted to those defects where more than five cases were exposed to the antihistamine of interest, generating 340 analyses which yielded 20 (5.9%) significant positive associations (adjusted ORs ranging from 1.21 to 4.34).

CONCLUSIONS

Only a few of our findings were consistent with previous studies. There is a lack of strong evidence to conclude that birth defects are associated with exposure to antihistamines during early pregnancy.

Congenital diaphragmatic hernia and maternal dietary nutrient pathways and diet quality

INTRODUCTION

We examined the association of congenital diaphragmatic hernia (CDH) with maternal dietary intake, using semi-Bayes hierarchical models and principal components analysis to consider intake of nutrients that contribute to one-carbon metabolism and oxidative stress pathways, and a diet quality index.

METHODS

We included data on 825 cases and 11,108 nonmalformed controls born from 1997-2011 whose mother participated in the National Birth Defects Prevention Study (NBDPS), a multisite, population-based case-control study. Exposure data were from maternal telephone interviews, which included a food frequency questionnaire. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were generated from logistic regression models that included nutritional factors as continuous variables and were adjusted for maternal energy intake, race-ethnicity, parity, and vitamin supplement intake.

RESULTS

In the semi-Bayes hierarchical model that included all nutrients and confounders, riboflavin was the only nutrient for which the 95% CI excluded 1.0; the aOR for a 1 SD increase was 0.83. The aORs were 0.79 (95% CI 0.69-0.91) for the one-carbon metabolism pathway score, 0.90 (95% CI 0.80-1.01) for oxidative stress, and 0.85 (95% CI 0.77-0.93) for diet quality (the aORs correspond to a 1 SD increase).

CONCLUSIONS

The findings from this study provide some support for the hypothesis that better prepregnancy nutrition is associated with reduced risk for CDH. These results provide etiologic clues but should be interpreted with caution given the novelty of the investigation.

A genome-wide association study implicates the BMP7 locus as a risk factor for nonsyndromic metopic craniosynostosis

Our previous genome-wide association study (GWAS) for sagittal nonsyndromic craniosynostosis (sNCS) provided important insights into the genetics of midline CS. In this study, we performed a GWAS for a second midline NCS, metopic NCS (mNCS), using 215 non-Hispanic white case-parent triads. We identified six variants with genome-wide significance (P ≤ 5 × 10-8): rs781716 (P = 4.71 × 10-9; odds ratio [OR] = 2.44) intronic to SPRY3; rs6127972 (P = 4.41 × 10-8; OR = 2.17) intronic to BMP7; rs62590971 (P = 6.22 × 10-9; OR = 0.34), located ~ 155 kb upstream from TGIF2LX; and rs2522623, rs2573826, and rs2754857, all intronic to PCDH11X (P = 1.76 × 10-8, OR = 0.45; P = 3.31 × 10-8, OR = 0.45; P = 1.09 × 10-8, OR = 0.44, respectively). We performed a replication study of these variants using an independent non-Hispanic white sample of 194 unrelated mNCS cases and 333 unaffected controls; only the association for rs6127972 (P = 0.004, OR = 1.45; meta-analysis P = 1.27 × 10-8, OR = 1.74) was replicated. Our meta-analysis examining single nucleotide polymorphisms common to both our mNCS and sNCS studies showed the strongest association for rs6127972 (P = 1.16 × 10-6). Our imputation analysis identified a linkage disequilibrium block encompassing rs6127972, which contained an enhancer overlapping a CTCF transcription factor binding site (chr20:55,798,821-55,798,917) that was significantly hypomethylated in mesenchymal stem cells derived from fused metopic compared to open sutures from the same probands. This study provides additional insights into genetic factors in midline CS.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and the risk of isolated congenital heart defects among offspring

BACKGROUND

Although there is evidence in experimental model systems that exposure to polycyclic aromatic hydrocarbons (PAHs) is linked with congenital heart defects (CHDs), few studies have examined the association in humans. We conducted a case-control study to examine the association between maternal exposure to PAHs and CHDs in offspring using data from the National Birth Defects Prevention Study (NBDPS) (1997-2011).

METHODS

We obtained detailed information on maternal occupation during the month before to three months after conception. Expert raters, masked to case-control status, assessed job descriptions to assign categorical levels of exposure. Categories were quantitatively mapped to estimate cumulative exposure to PAHs, incorporating exposure intensity, frequency, work duration, and work hours. Quartiles were generated for cumulative maternal exposure to PAHs. Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using unconditional logistic regression for quartiles of PAH exposure and six CHD groupings (e.g. conotruncal) and specific subtypes (e.g. tetralogy of Fallot [ToF]). Final models were adjusted for maternal age, race/ethnicity, education, smoking, anticonvulsant use, folic acid supplementation, and study center.

RESULTS

There were 4,775 case and 7,734 control infants eligible for the study. The prevalence of occupational exposure to PAHs was 10.2% among both case and control mothers. In adjusted analysis, compared to mothers with no occupational PAH exposure, those in the highest quartile of exposure were more likely to have offspring in the conotruncal heart defects group (OR 1.41; 95% CI 1.00-2.00), and with ToF (OR 1.83; 95% CI 1.21-2.78).

CONCLUSIONS

Women in the highest quartile of estimated cumulative occupational PAH exposure during early pregnancy were more likely to have offspring with conotruncal heart defects, specifically ToF, compared to women with no occupational PAH exposure. Other comparisons between PAHs and other CHDs subgroups did not show any statistically precise associations.

Vasoactive exposures and risk of amniotic band syndrome and terminal transverse limb deficiencies

INTRODUCTION

Amniotic band syndrome (ABS) includes limb deficiencies accompanied by fibrous strands originating from the amniotic lining. Terminal transverse limb deficiencies (TTLD) appear to be similar but lack fibrous strands. Both are hypothesized to result from vascular disruption. For ABS, limb deficiencies are considered secondary to amnion rupture. We explored an alternative possibility-that TTLD is the primary defect and ABS is secondary.

METHODS

Using data from the National Birth Defects Prevention Study, we expanded on a previous study. We examined smoking, alcohol, and medications categorized by indicated vasoactivity as markers of vascular disruption. Logistic regression models with Firth's penalized likelihood were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

Use of bronchodilators and aspirin appeared to increase the risk of ABS, while decongestants and nonaspirin NSAIDs increased the risk of TTLD. The risk of ABS was markedly increased in cases reporting combinations of vasoactive exposures, particularly alcohol and aspirin (aOR 3.7, 95% CI 1.6, 7.8), and alcohol and bronchodilators (aOR 3.4, 95% CI 1.4, 7.5). Increased risk of TTLD due to combinations of vasoactive exposures was only observed for smoking and decongestants (aOR 2.3, 95% CI 1.4, 3.6).

CONCLUSIONS

Exposures associated with increased risk of ABS had no apparent association with TTLD, supporting previous evidence that these may be distinct phenotypes. ABS appears to be associated with combined exposures with vasodilation properties, such as alcohol and bronchodilators, while increased risk of TTLD may be associated with smoking and decongestants, both vasoconstrictive exposures.

Acculturation and selected birth defects among non-Hispanic Blacks in a population-based case-control study

BACKGROUND

There are noted birth defects prevalence differences between race/ethnicity groups. For instance, non-Hispanic (NH) Black mothers are more likely to have an infant with encephalocele, although less likely to have an infant with anotia/microtia compared to NH Whites. When stratifying by nativity and years lived within the United States, additional variations become apparent.

METHODS

Data from the National Birth Defects Prevention Study were used to calculate descriptive statistics and estimate crude/adjusted odds ratios (aORs) and 95% confidence intervals (95%CIs) among NH Blacks with one of 30 major defects and non-malformed controls. Total case/controls were as follows: U.S.- (2,773/1101); Foreign- (343/151); African-born (161/64). Study participants were also examined by number of years lived in the U.S. (≤5 vs. 6+ years).

RESULTS

Compared to U.S.-born, foreign-born NH Black controls tended to be older, had more years of education, and were more likely to have a higher household income. They also had fewer previous livebirths and were less likely to be obese. In the adjusted analyses, two defect groups were significantly attenuated: limb deficiencies, aORs/95%CIs = (0.44 [0.20-0.97]) and septal defects (0.69 [0.48-0.99]). After stratifying by years lived in the United States, the risk for hydrocephaly (2.43 [1.03-5.74]) became apparent among those having lived 6+ years in the United States. When restricting to African-born mothers, none of the findings were statistically significant.

CONCLUSIONS

Foreign-born NH Blacks were at a reduced risk for a few selected defects. Results were consistent after restricting to African-born mothers and did not change considerably when stratifying by years lived in the United States.

Association between maternal occupational exposure to polycyclic aromatic hydrocarbons and rare birth defects of the face and central nervous system

BACKGROUND

Previous studies suggested associations between maternal smoking, a source of exposure to polycyclic aromatic hydrocarbons (PAHs) and other chemicals, and central nervous system and face birth defects; however, no previous studies have evaluated maternal occupational PAH exposure itself.

METHODS

Jobs held in the periconceptional period were retrospectively assigned for occupational PAH exposures. Associations between maternal occupational PAH exposure and selected rare defects of the face (cataracts, microphthalmia, glaucoma, microtia, and choanal atresia) and central nervous system (holoprosencephaly, hydrocephaly, cerebellar hypoplasia, and Dandy-Walker malformation) were evaluated using data from the National Birth Defects Prevention Study, a population-based case-control study in the United States. Crude and adjusted odds ratios (ORs) with 95% confidence intervals were calculated to estimate associations between each evaluated defect and PAH exposure using multivariable logistic regression.

RESULTS

Food and beverage serving, as well as cooks and food preparation occupations, were among the most frequent jobs held by exposed mothers. Cataracts, microtia, microphthalmia, and holoprosencephaly were significantly associated with PAH exposure with evidence of dose-response (P-values for trend ≤.05). Hydrocephaly was associated with any PAH exposure, but not significant for trend. Sensitivity analyses that reduced possible sources of exposure misclassification tended to strengthen associations.

CONCLUSIONS

This is the first population-based case-control study to evaluate associations between maternal occupational PAH exposures and these rare birth defects of the central nervous system and face.

Gene-by-gene interactions associated with the risk of conotruncal heart defects

BACKGROUND

The development of conotruncal heart defects (CTDs) involves a complex relationship among genetic variants and maternal lifestyle factors. In this article, we focused on the interactions between 13 candidate genes within folate, homocysteine, and transsulfuration pathways for potential association with CTD risk.

METHODS

Targeted sequencing was used for 328 case-parental triads enrolled in the National Birth Defects Prevention Study (NBDPS). To evaluate the interaction of two genes, we applied a conditional logistic regression model for all possible SNP pairs within two respective genes by contrasting the affected infants with their pseudo-controls. The findings were replicated in an independent sample of 86 NBDPS case-parental triads genotyped by DNA microarrays. The results of two studies were further integrated by a fixed-effect meta-analysis.

RESULTS

One SNP pair (i.e., rs4764267 and rs6556883) located in gene MGST1 and GLRX, respectively, was found to be associated with CTD risk after multiple testing adjustment using simpleM, a modified Bonferroni correction approach (nominal p-value of 4.62e-06; adjusted p-value of .04). Another SNP pair (i.e., rs11892646 and rs56219526) located in gene DNMT3A and MTRR, respectively, achieved marginal significance after multiple testing adjustment (adjusted p-value of .06).

CONCLUSION

Further studies with larger sample sizes are needed to confirm and elucidate these potential interactions.

The effects of occupational pollutants on the reproductive health of female informal street traders in Warwick junction, Durban, South Africa - a cross-sectional study

BACKGROUND

Informal street traders are exposed on a daily basis to traffic emissions and biomass fuel smoke containing a variety of pollutants. These exposures are likely to place the female traders at increased risk for adverse reproductive outcomes.

AIM

The aim of this study was to compare the reproductive outcomes among street traders exposed to pollutants from their work-related activities and traders without such exposure.

METHODS

A cross-sectional study was conducted among 305 female traders selected from exposed and non-exposed areas within the Warwick Junction trading hub, located in Durban, South Africa. Validated reproductive questionnaires and clinical assessments were conducted on all participants. Adverse reproductive outcomes such as low birth weight, spontaneous abortions and infertility were assessed.

RESULTS

The mean age of the traders was 43.6 years (SD:12.1), mostly single (63%) and worked in trading hub for an average of 14 years. There were 876 pregnancies reported in the total sample. Traders pregnant while working in this location accounted for 120 pregnancies There was an increased risk of exposed traders having a low birth weight infant as compared to non-exposed traders (OR = 3.7; CI: 1.8, 7.6). Exposed traders were also almost 3 times more likely to be infertile as compared to non-exposed traders (OR = 2.6; CI: 1.6, 4.3).

CONCLUSIONS

This study has demonstrated that female street traders working within a trading hub in KwaZulu-Natal, South Africa; exposed to occupational pollutants show an association with developing infertility and low birth weight infants. Recommendations to mitigate adverse exposures have been suggested which include short term safety interventions and better cooking practices and future long term policy interventions.

The effects of occupational pollutants on the reproductive health of female informal street traders in Warwick junction, Durban, South Africa - a cross-sectional study

BACKGROUND

Informal street traders are exposed on a daily basis to traffic emissions and biomass fuel smoke containing a variety of pollutants. These exposures are likely to place the female traders at increased risk for adverse reproductive outcomes.

AIM

The aim of this study was to compare the reproductive outcomes among street traders exposed to pollutants from their work-related activities and traders without such exposure.

METHODS

A cross-sectional study was conducted among 305 female traders selected from exposed and non-exposed areas within the Warwick Junction trading hub, located in Durban, South Africa. Validated reproductive questionnaires and clinical assessments were conducted on all participants. Adverse reproductive outcomes such as low birth weight, spontaneous abortions and infertility were assessed.

RESULTS

The mean age of the traders was 43.6 years (SD:12.1), mostly single (63%) and worked in trading hub for an average of 14 years. There were 876 pregnancies reported in the total sample. Traders pregnant while working in this location accounted for 120 pregnancies There was an increased risk of exposed traders having a low birth weight infant as compared to non-exposed traders (OR = 3.7; CI: 1.8, 7.6). Exposed traders were also almost 3 times more likely to be infertile as compared to non-exposed traders (OR = 2.6; CI: 1.6, 4.3).

CONCLUSIONS

This study has demonstrated that female street traders working within a trading hub in KwaZulu-Natal, South Africa; exposed to occupational pollutants show an association with developing infertility and low birth weight infants. Recommendations to mitigate adverse exposures have been suggested which include short term safety interventions and better cooking practices and future long term policy interventions.

Exome sequencing of family trios from the National Birth Defects Prevention Study: Tapping into a rich resource of genetic and environmental data

BACKGROUND

The National Birth Defects Prevention Study (NBDPS) is a multisite, population-based, case-control study of genetic and nongenetic risk factors for major structural birth defects. Eligible women had a pregnancy affected by a birth defect or a liveborn child without a birth defect between 1997 and 2011. They were invited to complete a telephone interview to collect pregnancy exposure data and were mailed buccal cell collection kits to collect specimens from themselves, their child (if living), and their child's father. Over 23,000 families representing more than 30 major structural birth defects provided DNA specimens.

METHODS

To evaluate their utility for exome sequencing (ES), specimens from 20 children with colonic atresia were studied. Evaluations were conducted on specimens collected using cytobrushes stored and transported in open versus closed packaging, on native genomic DNA (gDNA) versus whole genome amplified (WGA) products and on a library preparation protocol adapted to low amounts of DNA.

RESULTS

The DNA extracted from brushes in open packaging yielded higher quality sequence data than DNA from brushes in closed packaging. Quality metrics of sequenced gDNA were consistently higher than metrics from corresponding WGA products and were consistently high when using a low input protocol.

CONCLUSIONS

This proof-of-principle study established conditions under which ES can be applied to NBDPS specimens. Successful sequencing of exomes from well-characterized NBDPS families indicated that this unique collection can be used to investigate the roles of genetic variation and gene-environment interaction effects in birth defect etiologies, providing a valuable resource for birth defect researchers.