Marlene Anderka

The National Birth Defects Prevention Study.

The National Birth Defects Prevention Study was designed to identify infants with major birth defects and evaluate genetic and environmental factors associated with the occurrence of birth defects. The ongoing case-control study covers an annual birth population of 482,000 and includes cases identified from birth defect surveillance registries in eight states. Infants used as controls are randomly selected from birth certificates or birth hospital records. Mothers of case and control infants are interviewed and parents are asked to collect buccal cells from themselves and their infants for DNA testing. Information gathered from the interviews and the DNA specimens will be used to study independent genetic and environmental factors and gene-environment interactions for a broad range of birth defects. As of December 2000, 7470 cases and 3821 controls had been ascertained in the eight states. Interviews had been completed with 70% of the eligible case and control mothers, buccal cell collection had begun in all of the study sites, and researchers were developing analysis plans for the compiled data. This study is the largest and broadest collaborative effort ever conducted among the nations leading birth defect researchers. The unprecedented statistical power that will result from this study will enable scientists to study the epidemiology of some rare birth defects for the first time. The compiled interview data and banked DNA of approximately 35 categories of birth defects will facilitate future research as new hypotheses and improved technologies emerge.

Control Selection and Participation in an Ongoing, Population-based, Case-Control Study of Birth Defects The National Birth Defects Prevention Study

To evaluate the representativeness of controls in an ongoing, population-based, case-control study of birth defects in 10 centers across the United States, researchers compared 1997-2003 birth certificate data linked to selected controls (n = 6,681) and control participants (n = 4,395) with those from their base populations (n = 2,468,697). Researchers analyzed differences in population characteristics (e.g., percentage of births at > or =2,500 g) for each group. Compared with their base populations, control participants did not differ in distributions of maternal or paternal age, previous livebirths, maternal smoking, or diabetes, but they did differ in other maternal (i.e., race/ethnicity, education, entry into prenatal care) and infant (i.e., birth weight, gestational age, and plurality) characteristics. Differences in distributions of maternal, but not infant, characteristics were associated with participation by selected controls. Absolute differences in infant characteristics for the base population versus control participants were < or =1.3 percentage points. Differences in infant characteristics were greater at centers that selected controls from hospitals compared with centers that selected controls from electronic birth certificates. These findings suggest that control participants in the National Birth Defects Prevention Study generally are representative of their base populations. Hospital-based control selection may slightly underascertain infants affected by certain adverse birth outcomes.

WIC participation and pregnancy outcomes: Massachusetts Statewide Evaluation Project.

The effects of WIC prenatal participation were examined using data from the Massachusetts Birth and Death Registry. The birth outcomes of 4,126 pregnant women who participated in the WIC program and gave birth in 1978 were compared to those of 4,126 women individually matched on maternal age, race, parity, education, and marital status who did not participate in WIC. WIC prenatal participants are at greater demographic risk for poor pregnancy outcomes compare to all women in the same community. WIC participation is associated with improved pregnancy outcomes, including, a decrease in low birthweight (LBW) incidence (6.9 per cent vs 8.7 per cent) and neonatal mortality (12 vs 35 deaths), an increase in gestational age (40.0 vs 39.7 weeks), and a reduction in inadequate prenatal care (3.8 per cent vs 7.0 per cent). Stratification by demographic subpopulations indicates that subpopulations at higher risk (teenage, unmarried, and Hispanic origin women) have more enhanced pregnancy outcomes associated with WIC participation. Stratification by duration of participation indicates that increased participation is associated with enhanced pregnancy outcomes. While these findings suggest that birth outcome differences are a function of WIC participation, other factors which might distinguish between the two groups could also serve as the basis for alternative explanations.

Medications Used to Treat Nausea and Vomiting of Pregnancy and the Risk of Selected Birth Defects

BACKGROUND Nausea and vomiting of pregnancy (NVP) occurs in up to 80% of pregnant women, but its association with birth outcomes is not clear. Several medications are used for the treatment of NVP; however, data are limited on their possible associations with birth defects. METHODS Using data from the National Birth Defects Prevention Study (NBDPS)-a multi-site, population-based, case-control study-we examined whether NVP or its treatment was associated with the most common noncardiac defects in the NBDPS (nonsyndromic cleft lip with or without cleft palate [CL/P], cleft palate alone [CP], neural tube defects, and hypospadias) compared with randomly selected nonmalformed live births. RESULTS Among the 4524 cases and 5859 controls included in this study, 67.1% reported first-trimester NVP, and 15.4% of them reported using at least one agent for NVP. Nausea and vomiting of pregnancy was not associated with CP or neural tube defects, but modest risk reductions were observed for CL/P (adjusted odds ratio [aOR] = 0.87; 95% confidence interval [CI], 0.77-0.98) and hypospadias (aOR = 0.84; 95% CI, 0.72-0.98). Regarding treatments for NVP in the first trimester, the following adjusted associations were observed with an increased risk: proton pump inhibitors and hypospadias (aOR = 4.36; 95% CI, 1.21-15.81), steroids and hypospadias (aOR = 2.87; 95% CI, 1.03-7.97), and ondansetron and CP (aOR = 2.37; 95% CI, 1.18-4.76), whereas antacids were associated with a reduced risk for CL/P (aOR = 0.58; 95% CI, 0.38-0.89). CONCLUSIONS NVP was not observed to be associated with an increased risk of birth defects; however, possible risks related to three treatments (i.e., proton pump inhibitors, steroids and ondansetron), which could be chance findings, warrant further investigation.

Use of Antiepileptic Medications in Pregnancy in Relation to Risks of Birth Defects

PURPOSE To evaluate use of specific antiepileptic drugs (AEDs) in pregnancy in relation to specific birth defects. METHODS Using data from the National Birth Defects Prevention Study, we assessed use of AEDs and the risk of neural tube defects (NTDs), oral clefts (OCs), heart defects (HDs), hypospadias, and other major birth defects, taking specific agent, timing, and indication into consideration. RESULTS Drug-specific increased risks were observed for valproic acid in relation to NTDs [adjusted odds ratio (aOR), 9.7;, 95% confidence interval (CI), 3.4-27.5], OCs (aOR, 4.4; 95% CI, 1.6-12.2), HDs (aOR, 2.0; 95% CI, 0.78-5.3), and hypospadias (aOR. 2.4; 95% CI, 0.62-9.0), and for carbamazapine in relation to NTDs (aOR, 5.0; 95% CI, 1.9-12.7). Epilepsy history without AED use did not seem to increase risk. CONCLUSIONS Valproic acid, which current guidelines suggest should be avoided in pregnancy, was most notable in terms of strength and breadth of its associations. Carbamazapine was associated with NTDs, even after controlling for folic acid use. Sample sizes were still too small to adequately assess risks of less commonly used AEDs, but our findings support further study to identify lower risk options for pregnant women.

Nonsteroidal antiinflammatory drug use among women and the risk of birth defects

OBJECTIVE We examined whether the use of nonsteroidal antiinflammatory drugs (NSAIDs) in early pregnancy was associated with a range of structural birth defects. STUDY DESIGN Data were from the National Birth Defects Prevention Study, a multisite population-based, case-control study of risk factors for birth defects. RESULTS Among women in the National Birth Defects Prevention Study, 22.6% reported the use of NSAIDs in the first trimester of pregnancy, most commonly ibuprofen, aspirin, and naproxen. Of the 29 defect groups that were examined, most were not associated with NSAID use. Small-to-moderate increased risks of some oral cleft groups, some neural tube defect groups, anophthalmia/microphthalmia, pulmonary valve stenosis, amniotic bands/limb body wall defects, and transverse limb deficiencies were associated with ibuprofen, aspirin, and naproxen exposure. CONCLUSION The use of NSAIDs in early pregnancy does not appear to be a major risk factor for birth defects, although there were a few moderate associations between NSAIDs and specific birth defects.

The national birth defects prevention study: A review of the methods

BACKGROUND The National Birth Defects Prevention Study (NBDPS) is a large population-based multicenter case-control study of major birth defects in the United States. METHODS Data collection took place from 1998 through 2013 on pregnancies ending between October 1997 and December 2011. Cases could be live born, stillborn, or induced terminations, and were identified from birth defects surveillance programs in Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Texas, and Utah. Controls were live born infants without major birth defects identified from the same geographical regions and time periods as cases by means of either vital records or birth hospitals. Computer-assisted telephone interviews were completed with women between 6 weeks and 24 months after the estimated date of delivery. After completion of interviews, families received buccal cell collection kits for the mother, father, and infant (if living). RESULTS There were 47,832 eligible cases and 18,272 eligible controls. Among these, 32,187 (67%) and 11,814 (65%), respectively, provided interview information about their pregnancies. Buccal cell collection kits with a cytobrush for at least one family member were returned by 19,065 case and 6,211 control families (65% and 59% of those who were sent a kit). More than 500 projects have been proposed by the collaborators and over 200 manuscripts published using data from the NBDPS through December 2014. CONCLUSION The NBDPS has made substantial contributions to the field of birth defects epidemiology through its rigorous design, including case classification, detailed questionnaire and specimen collection, large study population, and collaborative activities across Centers.

Laterality defects in the national birth defects prevention study (1998-2007): birth prevalence and descriptive epidemiology.

Little is known epidemiologically about laterality defects. Using data from the National Birth Defects Prevention Study (NBDPS), a large multi‐site case‐control study of birth defects, we analyzed prevalence and selected characteristics in children born with laterality defects born from 1998 to 2007. We identified 517 nonsyndromic cases (378 heterotaxy, 73.1%; 139 situs inversus totalis [SIT], 26.9%) resulting in an estimated birth prevalence of 1.1 per 10,000 live births (95% confidence interval 1.0–1.2). Prevalence did not differ significantly across sites, over time, or by inclusion of pregnancy termination. Laterality defects were more common among preterm cases compared to term cases, and in children born to mothers who were non‐white or younger than 20 years compared to white mothers or those age 25–29 years. The distribution of associated cardiac and extra‐cardiac defects, excluding the expected heterotaxy anomalies, varied by type of laterality defect. Cases with heterotaxy were significantly more likely than those with SIT to have double outlet right ventricle, atrioventricular canal defects, pulmonary stenosis, non‐tetralogy of Fallot pulmonary atresia with ventricular septal defect, totally and partially anomalous pulmonary venous return; also more likely to have orofacial clefts, esophageal atresia, bowel atresias, and omphalocele, though not reaching statistical significance. Relatively more common among cases with SIT were Dandy‐Walker malformation, anotia/microtia, and limb deficiency. The similarity in the demographic characteristics of heterotaxy and SIT supports the hypothesis that they are part of a continuum of abnormal left‐right axis patterning. These findings on laterality defects may help guide clinical care, future research, and prevention strategies.

Maternal exposure to criteria air pollutants and congenital heart defects in offspring: results from the national birth defects prevention study.

Background: Epidemiologic literature suggests that exposure to air pollutants is associated with fetal development. Objectives: We investigated maternal exposures to air pollutants during weeks 2–8 of pregnancy and their associations with congenital heart defects. Methods: Mothers from the National Birth Defects Prevention Study, a nine-state case–control study, were assigned 1-week and 7-week averages of daily maximum concentrations of carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide and 24-hr measurements of fine and coarse particulate matter using the closest air monitor within 50 km to their residence during early pregnancy. Depending on the pollutant, a maximum of 4,632 live-birth controls and 3,328 live-birth, fetal-death, or electively terminated cases had exposure data. Hierarchical regression models, adjusted for maternal demographics and tobacco and alcohol use, were constructed. Principal component analysis was used to assess these relationships in a multipollutant context. Results: Positive associations were observed between exposure to nitrogen dioxide and coarctation of the aorta and pulmonary valve stenosis. Exposure to fine particulate matter was positively associated with hypoplastic left heart syndrome but inversely associated with atrial septal defects. Examining individual exposure-weeks suggested associations between pollutants and defects that were not observed using the 7-week average. Associations between left ventricular outflow tract obstructions and nitrogen dioxide and between hypoplastic left heart syndrome and particulate matter were supported by findings from the multipollutant analyses, although estimates were attenuated at the highest exposure levels. Conclusions: Using daily maximum pollutant levels and exploring individual exposure-weeks revealed some positive associations between certain pollutants and defects and suggested potential windows of susceptibility during pregnancy. Citation: Stingone JA, Luben TJ, Daniels JL, Fuentes M, Richardson DB, Aylsworth AS, Herring AH, Anderka M, Botto L, Correa A, Gilboa SM, Langlois PH, Mosley B, Shaw GM, Siffel C, Olshan AF, National Birth Defects Prevention Study. 2014. Maternal exposure to criteria air pollutants and congenital heart defects in offspring: results from the National Birth Defects Prevention Study. Environ Health Perspect 122:863–872; http://dx.doi.org/10.1289/ehp.1307289

Patterns of tobacco exposure before and during pregnancy.

Objectives. To describe maternal exposure to tobacco in the three months before conception and throughout pregnancy, examine risk factors associated with tobacco exposure in pregnancy and smoking cessation, assess use of pharmacotherapy for smoking cessation and evaluate birth outcomes by smoking status. Design. A cohort of women from a multi‐site United States study were asked retrospectively about their exposure to tobacco. Population. The study population was comprised of 4,667 mothers of non‐malformed control infants who participated in the National Birth Defects Prevention Study from 1997 to 2003. Methods. Using computer‐assisted telephone interview responses from this population‐based sample, we assessed patterns of maternal smoking and exposure to environmental tobacco smoke (ETS) as well as use of pharmacotherapy for quitting smoking during pregnancy. Results. Overall, 961 (20.6%) mothers reported any smoking and 1,401 (30.0%) reported any exposure to ETS at home or work during the three months before conception through pregnancy. Of the 961 smokers, 512 (53.3%) reportedly quit smoking before or during pregnancy, including 379 (74% of quitters) in the first trimester, and 420 (43.7%) continued to smoke throughout the pregnancy. Only 2.1% of smokers reportedly used pharmacotherapy to quit smoking anytime from three months before conception through pregnancy. Low birthweight and preterm delivery rates were lowest among offspring of non‐smokers and highest in offspring of those who continued to smoke throughout pregnancy. Conclusions. About one‐half of mothers who reported preconceptional smoking quit before or during pregnancy. Use of pharmacotherapy to quit smoking during pregnancy was not common.