Patterns of Prescription Medication Use during the First Trimester of Pregnancy in the United States, 1997-2018.

The objective of this analysis was to describe patterns of prescription medication use during pregnancy, including secular trends, with consideration of indication, and distributions of use within demographic subgroups. We conducted a descriptive secondary analysis using data from 9,755 women whose infants served as controls in two large United States case-control studies from 1997-2011 and 2014-2018. After excluding vitamin, herbal, mineral, vaccine, i.v. fluid, and topical products and over-the-counter medications, the proportion of women that reported taking at least one prescription medication in the first trimester increased over the study years, from 37% to 50% of women. The corresponding proportions increased with increasing maternal age and years of education, were highest for non-Hispanic White women (47%) and lowest for Hispanic women (24%). The most common indication for first trimester use of a medication was infection (12-15%). Increases were observed across the years for medications used for indications related to nausea/vomiting, depression/anxiety, infertility, thyroid disease, diabetes, and epilepsy. The largest relative increase in use among women was observed for medications to treat nausea/vomiting, which increased from 3.8% in the earliest years of the study (1997-2001) to 14.8% in 2014-2018, driven in large part by ondansetron use. Prescription medication use in the first trimester of pregnancy is common and increasing. Many medical conditions require treatments among pregnant women, often involving pharmacotherapy, which necessitates consideration of the risk and safety profiles for both mother and fetus.

Use of vasoactive medications in pregnancy and the risk of stillbirth among birth defect cases.

BACKGROUND: Many previous studies have identified risk factors for stillbirth, but few examine stillbirth among pregnancies affected with birth defects. Because many hypothesized etiologies of stillbirth work through vascular pathologies of the placenta, we examined maternal use of vasoactive medications in relation to stillbirth among pregnancies affected with birth defects. METHODS: Data were analyzed from the National Birth Defects Prevention Study (1997-2011). We examined use of nonsteroidal anti-inflammatory drugs (NSAIDs), decongestants, short- or long-acting beta-agonists (SABA/LABA), and antihypertensive medications in relation to pregnancies affected by birth defects ending in stillbirth compared to live birth. Associations were measured with odds ratios (ORs) for early pregnancy use and hazard ratios (HRs) for time-varying late pregnancy use. RESULTS: Among all birth defects (n = 12,394), the risk of stillbirth was associated with use of antihypertensive medications in early (odds ratio [OR]: 1.8; 95% confidence interval [CI]: 1.0, 3.1) and late pregnancy (HR: 2.0; 95% CI: 1.1, 3.6). Other vasoactive medications were not associated with increased risk of stillbirth. Of 27 specific defect groups, increased risks were observed for only one medication/defect pair: early decongestant use was more common among mothers of stillbirth versus live birth cases with spina bifida (OR: 2.4; 95% CI: 0.9, 6.5). CONCLUSION: This exploratory analysis of vasoactive medication use suggests that use of NSAIDs, decongestants, and SABA/LABA is not associated with increased risk of stillbirth among pregnancies affected with birth defects. Our finding of increased risks associated with antihypertensive medication use raises questions of confounding by indication, which we were not able to fully address.

Periconceptional nonsteroidal anti-inflammatory drug use, folic acid intake, and the risk of spina bifida.

BACKGROUND: Use of nonsteroidal anti-inflammatory drugs (NSAIDs) during pregnancy may increase risk for neural tube defects (NTDs), including spina bifida. Folic acid intake can prevent NTDs, but it is not known whether it modifies any risks associated with NSAID use. OBJECTIVES: To assess the impact of periconceptional NSAID use on the risk of spina bifida overall and stratified by folic acid intake. STUDY DESIGN: We analyzed 1998-2015 data from the Slone Epidemiology Center Birth Defects Study, a multi-site, case-control study. Mothers were interviewed to identify sociodemographic factors, behaviors, and exposures during pregnancy. Periconceptional NSAID use was defined as use of aspirin, ibuprofen, naproxen, or COX2 inhibitors within the month before or after the last menstrual period. Logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for NSAID use, adjusted for study center and race/ethnicity stratified by average daily folic acid intake above ("high FA") or below ("low FA") 400 mcg/day. RESULTS: We compared mothers of 267 infants with spina bifida to mothers of 6,233 nonmalformed controls. Among control mothers, 20% used NSAIDS periconceptionally (16% ibuprofen, 4% aspirin, 3% naproxen, and <1% COX-2 inhibitors). For any NSAID use, the aORs among low FA and high FA women were 1.70 (95% CI [1.13, 2.57]) and 1.09 (95% CI [0.69, 1.71]), respectively. CONCLUSIONS: We observed a small increase in the risk for spina bifida among infants born to women who used NSAIDs periconceptionally, but this risk was limited to those who had inadequate folic acid intake.

Maternal exposure to hydroxychloroquine and birth defects.

BACKGROUND: Hydroxychloroquine is a treatment for rheumatic disease and considered safe during pregnancy. Interest in hydroxychloroquine has increased as it is being examined as a potential treatment and prophylaxis for coronavirus disease 2019. Data on the risks of specific birth defects associated with hydroxychloroquine use are sparse. METHODS: Using data from two case-control studies (National Birth Defects Prevention Study and Slone Epidemiology Center Birth Defects Study), we described women who reported hydroxychloroquine use in pregnancy and the presence of specific major birth defects in their offspring. Cases had at least one major birth defect and controls were live-born healthy infants. Women self-reported medication use information in the few months before pregnancy through delivery. RESULTS: In total, 0.06% (19/31,468) of case and 0.04% (5/11,614) of control mothers in National Birth Defects Prevention Study, and 0.04% (11/29,838) of case and 0.05% (7/12,868) of control mothers in Birth Defects Study reported hydroxychloroquine use. Hydroxychloroquine users had complicated medical histories and frequent medication use for a variety of conditions. The observed birth defects among women taking hydroxychloroquine were varied and included nine oral cleft cases; the elevated observed:expected ratios for specific oral cleft phenotypes and for oral clefts overall had 95% confidence intervals that included 1.0. CONCLUSION: While teratogens typically produce a specific pattern of birth defects, the observed birth defects among the hydroxychloroquine-exposed women did not present a clear pattern, suggesting no meaningful evidence for the risk of specific birth defects. The number of exposed cases is small; results should be interpreted cautiously.

Trends in first-trimester nausea and vomiting of pregnancy and use of select treatments: Findings from the National Birth Defects Prevention Study.

BACKGROUND: Although nausea and vomiting of pregnancy (NVP) is common, the secular and demographic trends of NVP and its treatments are not well-studied. OBJECTIVES: To describe the prevalence and patterns of first-trimester NVP and selected treatments among controls in the National Birth Defects Prevention Study (NBDPS). METHODS: National Birth Defects Prevention Study is a population-based case-control study of birth defects in the United States (1997-2011). We collected self-reported data about NVP and use of commonly reported pharmacological and herbal/natural treatments (ondansetron, promethazine, pyridoxine, metoclopramide, doxylamine succinate, ginger, phosphorated carbohydrate solution, and prochlorperazine) from mothers of non-malformed control infants. We estimated the prevalence of NVP and selected treatments and examined secular and demographic trends (education, race/ethnicity, and maternal age) for such use, adjusting for study centre. RESULTS: Among 10 540 mothers of controls, 7393 women (70.1%) reported first-trimester NVP, and 12.2% of those used one or more of the commonly reported treatments. Specific treatment use varied after adjustment for study centre (ondansetron: 3.4%; promethazine: 4.2%; pyridoxine: 3.2%; metoclopramide: 0.7%; doxylamine succinate: 1.7%; ginger: 1.0%; phosphorated carbohydrate solution: 0.4%; and prochlorperazine: 0.3%). Treatment use increased for each agent over the study period. Women with more years of education reported more NVP and treatment use. White (72%), Hispanic (71%), and other race (73%) women reported more NVP than Black women (67%); White women used selected NVP treatments most frequently, and Black women used them more than Hispanic women. Though women aged 25-34 years reported more NVP (72%) than younger (69%) or older (67%) women, the frequency of medication use was similar among women aged 25-34 and ≥35, and lower among women aged <25 years. CONCLUSIONS: National Birth Defects Prevention Study controls reported NVP at frequencies similar to those previously reported. Of note, we observed an increase in use of selected treatments over time, and variations in NVP and treatments by study site and demographic factors.

Folic acid antagonist use before and during pregnancy and risk for selected birth defects.

BACKGROUND: Maternal folic acid (FA) intake before and during early pregnancy reduces the risk for neural tube defects (NTDs); evidence suggests it may also reduce the risk for oral clefts, urinary defects, and cardiac defects. We sought to re-examine the use of drugs, which affect folate metabolism, dihydrofolate reductase inhibiting (DHFRI) medications, and anti-epileptic drugs (AEDs), in data collected in the post-FA fortification era (1998+) in the Slone Birth Defects Study. METHODS: We assessed maternal DHFRI and AED use and risk for NTDs, oral clefts, and urinary and cardiac defects. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using logistic regression. We assessed daily average FA intake of ≥400 mcg as a potential effect modifier. RESULTS: We analyzed data from 10,209 control and 9,625 case mothers. Among controls, the prevalence of exposure to DHFRI medications was 0.3% and to AEDs was 0.5%. Maternal use of AEDs was associated with increased risks for NTDs (OR: 3.4; 95% CI: 1.5, 7.5), oral clefts (OR: 2.3; 95% CI: 1.3, 4.0), urinary defects (OR: 1.6; 95% CI: 1.0, 2.7), and cardiac defects (OR: 1.6; 95% CI: 1.1, 2.3); similar or further increased risks were found among those with FA intake ≥400 mcg per day. DHFRI use was rare and relative risk estimates were imprecise and consistent with the null. CONCLUSIONS: Similar to our previous analyses, we observed associations between AED use and these defects. For DHFRI exposure, we found no evidence for increased risk of these defects. Though statistical power to examine FA effect modification was low, we found no evidence of further protection among those with FA intake ≥400 mcg, with some associations somewhat stronger in this group.

Maternal Use of Specific Antidepressant Medications During Early Pregnancy and the Risk of Selected Birth Defects.

Importance: Antidepressants are commonly used during pregnancy, but limited information is available about individual antidepressants and specific birth defect risks. Objective: To examine associations between individual antidepressants and specific birth defects with and without attempts to partially account for potential confounding by underlying conditions. Design, Setting, and Participants: The population-based, multicenter case-control National Birth Defects Prevention Study (October 1997-December 2011) included cases with selected birth defects who were identified from surveillance systems; controls were randomly sampled live-born infants without major birth defects. Mothers of cases and controls participated in an interview after the expected delivery date. The data were analyzed after the completion of the National Birth Defects Prevent Study's data collection. Exposures: Self-reported antidepressant exposure was coded to indicate monotherapy exposure to antidepressants. Main Outcomes and Measures: We used multivariable logistic regression to calculate adjusted odds ratios (aORs) and 95% confidence intervals for associations between maternal antidepressant use and birth defects. We compared early pregnancy antidepressant-exposed women with those without antidepressant exposure and, to partially account for confounding by underlying maternal conditions, those exposed to antidepressants outside of the birth defect development critical period. Results: This study included 30 630 case mothers of infants with birth defects and 11 478 control mothers (aged 12-53 years). Early pregnancy antidepressant use was reported by 1562 case mothers (5.1%) and 467 control mothers (4.1%), for whom elevated aORs were observed for individual selective serotonin reuptake inhibitors (SSRIs) and selected congenital heart defects (CHD) (eg, fluoxetine and anomalous pulmonary venous return: aOR, 2.56; 95% CI, 1.10-5.93; this association was attenuated after partially accounting for underlying conditions: aOR, 1.89; 95% CI, 0.56-6.42). This pattern was observed for many SSRI-CHD combinations. Associations between SSRIs and non-CHD birth defects often persisted or strengthened after partially accounting for underlying conditions (eg, citalopram and diaphragmatic hernia: aOR, 5.11; 95% CI, 1.29-20.24). Venlafaxine had elevated associations with multiple defects that persisted after partially accounting for underlying conditions (eg, anencephaly and craniorachischisis: aOR, 9.14; 95% CI, 1.91-43.83). Conclusions and Relevance: We found some associations between maternal antidepressant use and specific birth defects. Venlafaxine was associated with the highest number of defects, which needs confirmation given the limited literature on venlafaxine use during pregnancy and risk for birth defects. Our results suggest confounding by underlying conditions should be considered when assessing risk. Fully informed treatment decision-making requires balancing the risks and benefits of proposed interventions against those of untreated depression or anxiety.

Tetanus, diphtheria, and pertussis vaccine (Tdap) in pregnancy and risk of major birth defects in the offspring.

BACKGROUND: The tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine is recommended during pregnancy to protect newborns against pertussis infection in the months prior to their primary pertussis vaccination. Although research on the safety of the vaccine has been reassuring, most previous studies have considered major malformations as a single outcome, and have not examined potential risks for specific malformations. METHODS: Using data from the Slone Epidemiology Center Birth Defects Study collected between 2006 and 2015, we identified exposures to Tdap vaccine in both early and late pregnancy and examined potential risks for specific malformations. We used logistic regression models to calculate propensity score-adjusted odds ratios (aORs) and 95% confidence intervals (CIs). RESULTS: We identified 2,357 women exposed to Tdap during pregnancy. For first trimester exposures, the risk estimate for malformations overall was 1.0 (0.7, 1.5). We had power to examine nine specific malformations and found adjusted odds ratios ranging from 0.7 to 1.3, none of which had confidence intervals that excluded 1.0. For second or third trimester exposures, we examined 15 malformations with potential late pregnancy etiology, and calculated adjusted risk estimates for nine of these. Risk estimates ranged from 0.5 to 1.9, with no lower confidence bounds that excluded 1.0. CONCLUSIONS: We observed no evidence of appreciable risks for selected specific major malformations associated with Tdap vaccine exposure during early or late pregnancy. As pertussis remains a public health concern and Tdap vaccination levels in pregnancy remain below desired levels, these data provide further reassurance regarding the current recommendations for Tdap vaccination in pregnancy.

Risk of Stillbirth for Fetuses With Specific Birth Defects.

OBJECTIVE: To estimate the risk of stillbirth (fetal death at 20 weeks of gestation or more) associated with specific birth defects. METHODS: We identified a population-based retrospective cohort of neonates and fetuses with selected major birth defects and without known or strongly suspected chromosomal or single-gene disorders from active birth defects surveillance programs in nine states. Abstracted medical records were reviewed by clinical geneticists to confirm and classify all birth defects and birth defect patterns. We estimated risks of stillbirth specific to birth defects among pregnancies overall and among those with isolated birth defects; potential bias owing to elective termination was quantified. RESULTS: Of 19,170 eligible neonates and fetuses with birth defects, 17,224 were liveborn, 852 stillborn, and 672 electively terminated. Overall, stillbirth risks ranged from 11 per 1,000 fetuses with bladder exstrophy (95% CI 0-57) to 490 per 1,000 fetuses with limb-body-wall complex (95% CI 368-623). Among those with isolated birth defects not affecting major vital organs, elevated risks (per 1,000 fetuses) were observed for cleft lip with cleft palate (10; 95% CI 7-15), transverse limb deficiencies (26; 95% CI 16-39), longitudinal limb deficiencies (11; 95% CI 3-28), and limb defects due to amniotic bands (110; 95% CI 68-171). Quantified bias analysis suggests that failure to account for terminations may lead to up to fourfold underestimation of the observed risks of stillbirth for sacral agenesis (13/1,000; 95% CI 2-47), isolated spina bifida (24/1,000; 95% CI 17-34), and holoprosencephaly (30/1,000; 95% CI 10-68). CONCLUSION: Birth defect-specific stillbirth risk was high compared with the U.S. stillbirth risk (6/1,000 fetuses), even for isolated cases of oral clefts and limb defects; elective termination may appreciably bias some estimates. These data can inform clinical care and counseling after prenatal diagnosis.

Oseltamivir exposure in pregnancy and the risk of specific birth defects.

BACKGROUND: Influenza during pregnancy contributes to maternal morbidity and mortality. Neuraminidase inhibitors, including oseltamivir, are recommended for treating women with influenza during pregnancy. METHODS: Data from the Slone Birth Defects Study from 2009 to 2015 were used to investigate associations between oseltamivir and specific birth defects. We classified exposures according to timing in pregnancy and examined 52 and 16 defects with early and potential late pregnancy etiology, respectively; we calculated crude odds ratios (ORs) and 95% confidence intervals (CIs) for defects with three or more exposures. RESULTS: Among 8,379 cases and 4,190 nonmalformed controls, we identified 79 and 42 oseltamivir exposures, respectively. The majority of defects had no exposures. ORs were elevated for several defects, but the CI excluded the null only for intestinal malrotation (OR: 10.7 [1.8, 45.2]; three exposures). CONCLUSIONS: Largely null findings for specific defects are reassuring. The association with intestinal malrotation, while unstable, warrants further investigation.

Periconceptional folic acid and risk for neural tube defects among higher risk pregnancies.

BACKGROUND: Women with a previous neural tube defect (NTD)-affected pregnancy are recommended to consume 4,000 µg daily folic acid (FA) for prevention (10 times the general-population recommendation). Protection from doses between 400 and 4,000 µg for this and other higher risk groups is unclear. METHODS: In the case-control Slone Birth Defects Study (1988-2015), we examined the associations between periconceptional FA doses and NTDs among four higher risk groups: NTD family history, periconceptional antiepileptic drug exposure (AED), pregestational diabetes, and prepregnancy obesity. Mothers completed standardized interviews about pregnancy events and exposures. FA categorizations were based on (a) supplements only and (b) supplements and diet ("total folate"). We estimated odds ratios (ORs) and 95% confidence intervals (CIs) (adjusted for age and study center) using logistic regression. RESULTS: Cases and controls included: 45 and 119 with family history, 25 and 108 with AED exposure, 12 and 63 with pregestational diabetes, 111 and 1,243 with obesity. Daily FA supplementation was associated with lower NTD risk compared to no supplementation (adjusted ORs were 0.33 [95% CI 0.13, 0.76] for family history, 0.31 [0.09, 0.95] for AED exposure, 0.25 [0.04, 1.05] for pregestational diabetes, 0.65 [0.40, 1.04] for obesity). Though estimates were imprecise, as total folate increased stronger point estimates were observed, notably among family history. No mothers with a prior NTD-affected pregnancy supplemented with 4,000 µg. CONCLUSIONS: Our findings reinforce that all women of childbearing potential should consume at least 400 µg FA/day to protect against NTDs. Higher risk groups may benefit from higher doses.

One-Carbon Cofactor Intake and Risk of Neural Tube Defects Among Women Who Meet Folic Acid Recommendations: A Multicenter Case-Control Study.

We aimed to investigate associations between individual and concurrent (≥2) intakes of one-carbon cofactors vitamins B6 and B12, choline, betaine, and methionine and neural tube defect (NTD) outcomes among mothers meeting the folic acid recommendations. In the Slone Birth Defects Study (case-control design; North America, 1998-2015), mothers of 164 NTD cases and 2,831 nonmalformed controls completed food frequency questionnaires and structured interviews. Estimated intakes of one-carbon cofactors were dichotomized (high vs. low) for all except betaine (low or middle vs. high). We used logistic regression models to estimate odds ratios and 95% confidence intervals adjusted for center, age, and race. The analysis was restricted to mothers with estimated daily total folate intake of ≥400 µg during periconception. Fewer cases, compared with controls, had high intakes for each one-carbon cofactor except betaine, where the starkest contrast occurred in the middle group. Women with concurrent high intakes of B6, B12, choline, and methionine and moderate intake of betaine had approximately half the risk of an NTD-affected pregnancy (odds ratio = 0.49, 95% confidence interval: 0.23, 1.08). These findings suggest that, in the presence of folic acid, one-carbon cofactors-notably when consumed together-might reduce NTD risk. Additional research should inform any changes to clinical recommendations.

Use of benzodiazepine medications during pregnancy and potential risk for birth defects, National Birth Defects Prevention Study, 1997-2011.

BACKGROUND: Benzodiazepine medications can be used to treat anxiety, a condition affecting 15% of women of childbearing age in the United States. Studies have shown conflicting results for the association between benzodiazepine use during pregnancy and birth defects. METHODS: We analyzed 1997-2011 data from the National Birth Defects Prevention Study, a multisite, population-based case-control study. We assessed the prevalence of and factors associated with benzodiazepine use in pregnancy among mothers of live-born infants without a birth defect (control mothers). We used logistic regression to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for the association between specific birth defects and benzodiazepine use; we estimated crude odds ratios (cORs) for defect categories with 3-4 exposed cases. RESULTS: Exposure to benzodiazepines during pregnancy was rare (N = 93/11,614; 0.8%). Benzodiazepine use was more common among control mothers who were ≥30 years, non-Hispanic white, had more education, smoked, and took antidepressant medication. We observed significantly elevated ORs for any benzodiazepine and Dandy-Walker malformation (cOR: 3.1; 95% CI: 1.1, 8.6); for alprazolam and anophthalmia or microphthalmia (cOR: 4.0; 95% CI: 1.2, 13.1) and esophageal atresia or stenosis (aOR: 2.7; 95% CI: 1.2, 5.9); and lorazepam and pulmonary valve stenosis (cOR: 4.1; 95% CI: 1.2, 14.2), but sample sizes were limited and therefore CIs were wide. CONCLUSIONS: Our findings suggest that benzodiazepines use is rare and may be associated with risk for certain birth defects. However, these results need replication and should be interpreted with caution.

Validity of maternal recall of gestational age and weight at birth: Comparison of structured interview and medical records.

PURPOSE: To assess agreement between maternal recall and medical records for gestational age (GA) at birth as derived from dating information and birthweight. METHODS: In the case-control Slone Birth Defects Study, within 6 months of delivery, trained nurses conducted standardized telephone interviews with mothers of infants with and without major structural malformations. In a subset of approximately 5000 case and control mothers from five US centers (2008-2012), a research nurse abstracted subjects' medical records. GA at delivery was calculated as date of delivery minus (estimated date of confinement [EDC] minus 280); if EDC was unknown, last menstrual period served as a proxy for start of pregnancy. Positive and negative predictive values (PPV and NPV, respectively) were calculated, using medical records as the standard, for categories of GA at delivery (ie, early preterm <238, late preterm <258, and term ≥259 d) and birthweight (low <2500, normal 2500 to 4500, and high >4500 g). RESULTS: The gestational age and birthweight validation samples comprised 3122 and 4760 women, respectively, with diverse characteristics. The PPV and NPV were high (>92% and >99%, respectively) for all categories of delivery GA and birthweight. CONCLUSIONS: Our findings suggest that mothers' recall may be a valid alternative to medical records to estimate delivery GA and birthweight. This study used standardized interviews conducted by trained research nurses, had a short recall period (<6 months post delivery), and for delivery GA, focused on date-derived GA. Further research is needed on the potential impact of study design, population characteristics, and comparison to other data sources.

Risk factors for congenital microcephaly in the pre-Zika era.

BACKGROUND: The Zika epidemic has brought increased attention to congenital microcephaly as a birth outcome. However, little is known about risks for microcephaly unrelated to Zika. METHODS: Using data from the Slone Epidemiology Center Birth Defects Study from 1993 to 2015, we identified 57 cases of microcephaly alone ("isolated") and 109 cases of microcephaly that included other major birth defects ("non-isolated"), and considered a large number of potential risk factors including demographic characteristics, illnesses, and medications used during pregnancy. Where numbers permitted, we used logistic regression models to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). RESULTS: Substantial differences in risk factors were observed for isolated versus non-isolated microcephaly. For isolated microcephaly, risk estimates were elevated for mothers of non-Hispanic, non-White race/ethnicity, and underweight pre-pregnancy body mass index (BMI). The risk for exposure anytime in pregnancy to acetaminophen was null; in contrast, the aOR for NSAIDs was 2.4 (95% CI: 1.3-4.2). This association was weakened (but not eliminated) after excluding those exposed to opioids or illicit drugs, and risk was not present among those reporting less frequent exposures. For non-isolated microcephaly, elevated risk estimates were found for urinary tract infection. CONCLUSIONS: Risk factors differed for isolated and non-isolated microcephaly. While some findings support previously reported associations, (e.g., smoking, alcohol, underweight BMI), we also identified risk factors not previously described, notably NSAID use for isolated microcephaly and urinary tract infection for non-isolated microcephaly; however, these results should be viewed as hypothesis generating.

An application of data mining to identify potential risk factors for anophthalmia and microphthalmia.

BACKGROUND: We examined a large number of variables to generate new hypotheses regarding a wider range of risk factors for anophthalmia/microphthalmia using data mining. METHODS: Data were from the National Birth Defects Prevention Study, a multicentre, case-control study from 10 centres in the United States. There were 134 cases of "isolated" and 87 "nonisolated" (with other major birth defects) of anophthalmia/microphthalmia and 11 052 nonmalformed controls with delivery dates October 1997-December 2011. Using random forest, a data mining procedure, we compared the two case types with controls for 201 variables. Variables considered important ranked by random forest were included in a multivariable logistic regression model to estimate odds ratios and 95% confidence intervals. RESULTS: Predictors for isolated cases included paternal race/ethnicity, maternal intake of certain nutrients and foods, and childhood health problems in relatives. Using regression, inverse associations were observed with greater maternal education and with increasing intake of folate and potatoes. Odds were slightly higher with greater paternal education, for increased intake of carbohydrates and beans, and if relatives had a childhood health problem. For nonisolated cases, predictors included paternal race/ethnicity, maternal intake of certain nutrients, and smoking in the home the month before conception. Odds were higher for Hispanic fathers and smoking in the home and NSAID use the month before conception. CONCLUSIONS: Results appear to support previously hypothesised risk factors, socio-economic status, NSAID use, and inadequate folate intake, and potentially provide new areas such as passive smoking pre-pregnancy, and paternal education and ethnicity, to explore for further understanding of anophthalmia/microphthalmia.

Ondansetron for Treatment of Nausea and Vomiting of Pregnancy and the Risk of Specific Birth Defects.

OBJECTIVE: To use data from two large studies of birth defects to describe time trends in ondansetron use for the treatment of first-trimester nausea and vomiting of pregnancy and to investigate associations, either previously reported or undescribed, between first-trimester ondansetron use and major birth defects. METHODS: We used data from two case-control studies, the National Birth Defects Prevention Study (1997-2011) and the Slone Birth Defects Study (1997-2014). The prevalence of ondansetron use for the treatment of first-trimester nausea and vomiting of pregnancy among control patients was calculated in 2-year intervals. Using women with untreated first-trimester nausea and vomiting of pregnancy as the reference, we calculated adjusted odds ratios (ORs) and 95% CIs for associations between first-trimester ondansetron use for treatment of nausea and vomiting of pregnancy and specific birth defects. A secondary exposure group of other prescription antiemetics was used to address confounding by indication. RESULTS: In the National Birth Defects Prevention Study and Slone Birth Defects Study, respectively, 6,751 and 5,873 control mothers and 14,667 and 8,533 case mothers who reported first-trimester nausea and vomiting of pregnancy were included in the analysis. Among women in the control group, ondansetron exposure increased from less than 1% before 2000 to 13% in 2013-2014. Ondansetron use was not associated with an increased risk for most of the 51 defect groups analyzed. Modest increases in risk were observed for cleft palate (adjusted OR 1.6, 95% CI 1.1-2.3) in the National Birth Defects Prevention Study and renal agenesis-dysgenesis (adjusted OR 1.8, 95% CI 1.1-3.0) in the Birth Defects Study, although these findings may be the result of chance. CONCLUSION: Off-label use of ondansetron for the treatment of nausea and vomiting of pregnancy increased to 13% by the end of the study period. For the majority of specific birth defects investigated, there was no increased risk associated with first-trimester use of ondansetron for treatment of nausea and vomiting of pregnancy compared with no treatment, although modest associations with cleft palate and renal agenesis-dysgenesis warrant further study.

Metformin in the first trimester and risks for specific birth defects in the National Birth Defects Prevention Study.

BACKGROUND: We assessed associations between first-trimester metformin use for pregestational diabetes and specific major birth defects. METHODS: We compared risks associated with first-trimester metformin use by diabetic women to nondiabetic women on no diabetes medication; we calculated crude odds ratios by exact logistic regression and adjusted by inverse probability weighting. Confounding by diabetes was assessed by comparing risks for metformin-exposed diabetic women to those for insulin-exposed diabetics and nondiabetics treated with metformin for subfertililty. RESULTS: Among 9,279 nonmalformed controls and 24,375 malformed cases, diabetics who used metformin (with or without insulin) had increased adjusted odds ratios (aORs) for several birth defects associated with diabetes. However, women treated with metformin for subfertility had aORs similar to or lower than those for diabetic metformin users, and many approximated the null. For atrial septal defect secundum, anorectal defects, and limb reduction defects, the estimates for metformin when used for subfertility were 2-3-fold. CONCLUSION: While metformin use for diabetes was associated with an increased risk of many birth defects, when metformin was used for subfertility most defects had aORs that approximated the null, while only three defects had modestly increased aORs, two of which had lower confidence bounds that included the null. Our study does not suggest that metformin poses an appreciable risk for major birth defects, but further studies are necessary.

Periconceptional maternal fever, folic acid intake, and the risk for neural tube defects.

PURPOSE: Previous studies have shown an association between maternal fever in early pregnancy and neural tube defects (NTDs) such as spina bifida. Periconceptional folic acid intake has been shown to reduce the risk of these outcomes. METHODS: Using data from the Slone Epidemiology Center Birth Defects Study (1998-2015), we examined the impact of folic acid on the relationship between maternal fever in the periconceptional period (28 days before and after the last menstrual period) and NTDs. Logistic regression models were used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Mothers of 375 cases and 8247 nonmalformed controls were included. We observed an elevated risk for NTDs for fever in the periconceptional period (OR: 2.4; 95% CI: 1.5-4.0). This association was weaker for mothers who reported consuming the recommended amount of folic acid (≥400 µg per day; OR: 1.8; 95% CI: 0.8-4.0) than mothers with low folic acid intake (<400 µg per day; OR: 4.2; 95% CI: 2.2-8.2). CONCLUSIONS: Our data support an association between maternal periconceptional fever and an increased risk for NTDs and also provide evidence that this association was attenuated for mothers who reported consuming folic acid at recommended levels in the periconceptional period.