Safety of the 2010-11, 2011-12, 2012-13, and 2013-14 seasonal influenza vaccines in pregnancy: Birth defects, spontaneous abortion, preterm delivery, and small for gestational age infants, a study from the cohort arm of VAMPSS.

INTRODUCTION: There is a need for pregnancy safety information overall and for each seasonal formulation of the influenza vaccine. METHODS: As part of the cohort arm of the Vaccines and Medications in Pregnancy Surveillance System, vaccine-exposed and unexposed women in the U.S. or Canada were recruited during pregnancy in the 2010-2014 vaccine seasons and followed to pregnancy outcome. For the four seasons combined, crude and adjusted relative risks (RRs) were estimated with 95% confidence intervals (CIs) for major birth defects overall and infants small for gestational age. Crude and adjusted hazard ratios (HRs) were estimated with 95% CIs for spontaneous abortion and preterm delivery. Specific influenza season subanalyses were also conducted. RESULTS: Of 1730 women, 1263 were exposed to an influenza vaccine and 467 were unexposed to any influenza vaccine. Among pregnancies with first-trimester exposure excluding lost-to-follow-up, 26/457 (5.7%) resulted in an infant with a major birth defect compared to 13/427 (3.0%) in the unexposed (RR 1.87, 95% CI 0.97, 3.59). No specific pattern of defects was evident in the vaccine-exposed cohort. The overall risk of spontaneous abortion was not elevated (HR 1.09, 95% CI 0.49, 2.40). Adjusted HRs for preterm delivery approximated 1.0 (adjusted HR 1.23, 95% CI 0.75, 2.02). RRs for small for gestational age infants on weight, length and head circumference ranged from 1.19 to 1.49 with all CIs including 1. Season-by-season analyses resulted in variation by season; however, estimates were based on small numbers. CONCLUSIONS: Combining the 2010-2014 influenza seasons, we found a moderately elevated RR for major birth defects overall, but no evidence of a specific pattern; 95% CIs included 1, and this finding could be due to chance. In the combined seasons, we found no meaningful evidence of an increased risk for spontaneous abortion or preterm delivery following exposure to the seasonal influenza vaccine.

Safety of the 2011-12, 2012-13, and 2013-14 seasonal influenza vaccines in pregnancy: Preterm delivery and specific malformations, a study from the case-control arm of VAMPSS.

BACKGROUND: Pregnant women have higher risks of influenza complications, but vaccine coverage is incomplete. Because concern about fetal harm limits uptake, we investigated risks for preterm delivery (PTD) and specific birth defects following vaccination in the 2011-12 through 2013-14 influenza seasons. METHODS: We used data from the Slone Epidemiology Center's Birth Defects Study. For PTD, propensity score-adjusted time-varying hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for exposure anytime in pregnancy and for each trimester. For 42 specific major birth defects or birth defect categories, propensity score-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. RESULTS: For PTD (1803 fullterm deliveries, 107 PTD for all seasons combined), an elevated adjusted risk was observed for only the 2nd trimester of the 2011-12 season (HR=2.60, 95% CI 1.21, 5.61) - a reduction in gestational length of <2days. For the 42 specific defects or categories of defects (2866 cases, 1411 controls for all seasons combined) most adjusted risks were close to 1.0; the highest was 2.38 for omphalocele and the lowest was 0.50 for atrioventricular canal defects. None had lower confidence bounds >1.0. For each season separately, only one elevated OR had a lower 95% CI >1.0: omphalocele in 2011-12 (OR=5.19, 95% CI 1.44, 18.7). CONCLUSIONS: Our results regarding risks for PTD and birth defects are generally reassuring. The few risks that were observed are compatible with chance, but warrant testing in other data. Given that vaccine components and manufacturing processes vary, continuing studies are needed to evaluate risks and safety of each season's vaccine and specific products.

Application of data screening to drug exposure in large risk factor studies of birth defects.

BACKGROUND: Birth defects are the leading cause of infant death. While causes of most are unknown, those that might be due to medication use are among the most preventable. This study describes an approach to identifying those medications that most warrant attention by using a "screen" program that calculates odds ratios for pairs of exposures and specific birth defects. METHODS: We discuss the development of this tool and illustrate its application to two large risk factor studies, the Slone Epidemiology Center's Birth Defects Study and the Centers for Disease Control and Prevention's National Birth Defects Prevention Study, ideal settings for the systematic study of risks and relative safety of drugs in relation to birth defects while recognizing the inherent limitations of such an approach. RESULTS: Suggestions for establishing criteria for exposures and outcomes that balance the need for specific details with the practical considerations of sample size and volume of output are presented. Selection of appropriate exposure reference categories and control groups is also discussed, as well as the need to address potential confounding. An example that motivated a detailed investigation of possible associations between a medication (butalbital) and selected specific birth defects is provided. CONCLUSION: While screening programs such as the one described can be a valuable tool for exploring potential associations in large data bases, they must be applied with caution. The issue of multiple testing and chance findings is a major concern. While statistics are a necessary component, human judgment must be an integral part of the process.

Specific SSRIs and birth defects: Bayesian analysis to interpret new data in the context of previous reports.

OBJECTIVE: To follow up on previously reported associations between periconceptional use of selective serotonin reuptake inhibitors (SSRIs) and specific birth defects using an expanded dataset from the National Birth Defects Prevention Study. DESIGN: Bayesian analysis combining results from independent published analyses with data from a multicenter population based case-control study of birth defects. SETTING: 10 centers in the United States. PARTICIPANTS: 17,952 mothers of infants with birth defects and 9857 mothers of infants without birth defects, identified through birth certificates or birth hospitals, with estimated dates of delivery between 1997 and 2009. EXPOSURES: Citalopram, escitalopram, fluoxetine, paroxetine, or sertraline use in the month before through the third month of pregnancy. Posterior odds ratio estimates were adjusted to account for maternal race/ethnicity, education, smoking, and prepregnancy obesity. MAIN OUTCOME MEASURE: 14 birth defects categories that had associations with SSRIs reported in the literature. RESULTS: Sertraline was the most commonly reported SSRI, but none of the five previously reported birth defects associations with sertraline was confirmed. For nine previously reported associations between maternal SSRI use and birth defect in infants, findings were consistent with no association. High posterior odds ratios excluding the null value were observed for five birth defects with paroxetine (anencephaly 3.2, 95% credible interval 1.6 to 6.2; atrial septal defects 1.8, 1.1 to 3.0; right ventricular outflow tract obstruction defects 2.4, 1.4 to 3.9; gastroschisis 2.5, 1.2 to 4.8; and omphalocele 3.5, 1.3 to 8.0) and for two defects with fluoxetine (right ventricular outflow tract obstruction defects 2.0, 1.4 to 3.1 and craniosynostosis 1.9, 1.1 to 3.0). CONCLUSIONS: These data provide reassuring evidence for some SSRIs but suggest that some birth defects occur 2-3.5 times more frequently among the infants of women treated with paroxetine or fluoxetine early in pregnancy.

Seasonal influenza vaccination during pregnancy and the risks of preterm delivery and small for gestational age birth.

BACKGROUND: Influenza vaccination is routinely recommended for pregnant women, yet information on perinatal outcomes is sparse. METHODS: We investigated the associations between trivalent (seasonal) influenza vaccination during pregnancy and the risks of preterm delivery (PTD, live birth <37 weeks gestation) and small for gestational age birth (SGA, <10th percentile in weight for sex-specific gestational age) during the influenza seasons 2006-07 through 2009-10. The study population included 1619 mothers of live-born, non-malformed singleton infants interviewed as part of the Slone Epidemiology Center's Birth Defects Study. Associations between influenza vaccination and PTD and SGA were assessed using Cox and logistic regression models, respectively, with propensity scores used to adjust for confounding. Women vaccinated against pandemic H1N1 were excluded from the analysis. RESULTS: Influenza vaccination during pregnancy showed a near null association with PTD for influenza seasons 2006-07 through 2008-09 compared with unvaccinated women [adjusted hazard ratios (aHR) ranged from 0.79 [95% confidence interval (CI) 0.28, 2.21] in 2007-08 to 1.08 [95% CI: 0.40, 2.95] in 2008-09]. For 2009-10, the risk of PTD was higher in vaccinated women (aHR, 7.81 [95% CI: 2.66, 23.0]). Influenza vaccination was not associated with appreciable risks for SGA for all seasons with sufficient numbers of exposed SGA. CONCLUSION: Though limited by study size, these findings add support to previous observations of little or no increased risk of PTD or SGA associated with seasonal influenza vaccination for three of the four influenza seasons in our study. The increased risk of PTD observed for the 2009-10 influenza season warrants further investigation.

Use of selective serotonin-reuptake inhibitors during pregnancy and the risk of clubfoot.

BACKGROUND: Selective serotonin-reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressants. Previous studies have suggested that SSRIs may increase the risk of birth defects, including clubfoot. Using data from a population-based case-control study, we evaluated whether SSRI use increased the risk of clubfoot. METHODS: Mothers were interviewed within 1 year after delivery about sociodemographic factors, pregnancy events, and exposures. They were specifically asked if they experienced depression or anxiety or if they took any of the following SSRIs: citalopram, escitalopram, fluvoxamine, paroxetine, sertraline, or fluoxetine. We used logistic regression models to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: We included a total of 622 clubfoot cases and 2002 nonmalformed controls born between 2006 and 2011 in Massachusetts, New York, and North Carolina. For the 2nd or 3rd lunar month of pregnancy (the relevant gestational period), SSRI use for a period of more than 30 days was higher in case mothers (5%) than control mothers (3%). After adjustment for maternal smoking and body mass index, the OR for any SSRI use and clubfoot was 1.8 (95% CI = 1.1-2.8). When individual SSRIs were examined, ORs were elevated for sertraline (1.6 [0.8-3.2]), paroxetine (9.2 [0.7-484.6]), and escitalopram (2.9 [1.1-7.2]). CONCLUSION: Our data suggest an increased risk of clubfoot occurrence in relation to SSRI use. Drug-specific risks varied widely, and some estimates were unstable.

First-trimester exposure to bupropion and risk of cardiac malformations.

PURPOSE: Bupropion is a drug uniquely used both to treat depression and as an aid to smoking cessation. We investigated previously reported associations between first-trimester exposure to bupropion and cardiac defects. METHODS: Using data gathered since 2003 by the Slone Epidemiology Center's Case-control Birth Defects Study, we classified subjects with cardiac defects into subgroups. Exposure categories included first-trimester bupropion alone or in combination with other antidepressants, first-trimester antidepressants other than bupropion, and no exposure to any antidepressant at any time from 2 months prior to pregnancy through delivery. We calculated odds ratios and 95% confidence intervals, controlling for confounding using logistic regression. RESULTS: There were 8611 non-malformed infants and 7913 infants with cardiac defects. Eight cardiac subgroups had sufficient subjects (two or more exposed cases) for analysis. The adjusted odds ratio (aOR) for first-trimester bupropion use in relation to ventricular septal defect (VSD) was slightly elevated (1.6, 95% confidence interval 1.0-2.8); for exposure to bupropion alone, the aOR was 2.5 (95% confidence interval 1.3-5.0). Risks were not materially elevated for bupropion in relation to the other seven cardiac subgroups. CONCLUSIONS: We did not confirm previously reported associations for left-sided defects overall but had too few exposed cases to evaluate specific defects in this category. We did observe an elevated risk of VSD following first-trimester bupropion use, particularly when used without other antidepressants. This pattern for bupropion alone was observed in all our risk comparisons and was not explained by higher doses or gestational timing.

Maternal butalbital use and selected defects in the national birth defects prevention study.

BACKGROUND: Butalbital is a barbiturate contained in combination products with caffeine and an analgesic prescribed for the treatment of migraine and tension-type headaches. Controversy exists as to whether butalbital should continue to be prescribed in the United States because of the potential for abuse, overuse headache, and withdrawal syndromes. Butalbital crosses the placenta but there is limited information about potential teratogenicity. OBJECTIVE: To evaluate associations between butalbital and a wide range of specific birth defects. METHODS: The National Birth Defects Prevention Study is an ongoing, case-control study of nonsyndromic, major birth defects conducted in 10 states. The detailed case classification and large number of cases in the National Birth Defects Prevention Study allowed us to examine the association between maternal self-reported butalbital use and specific birth defects. We conducted an analysis of 8373 unaffected controls and 21,090 case infants with estimated dates of delivery between 1997 and 2007; included were birth defects with 250 or more cases. An exploratory analysis examined groups with 100 to 249 cases. RESULTS: Seventy-three case mothers and 15 control mothers reported periconceptional butalbital use. Of 30 specific defect groups evaluated, adjusted odds ratios for maternal periconceptional butalbital use were statistically significant for 3 congenital heart defects: tetralogy of Fallot (adjusted odds ratio = 3.04; 95% confidence interval = 1.07-8.62), pulmonary valve stenosis (adjusted odds ratio = 5.73; 95% confidence interval = 2.25-14.62), and secundum-type atrial septal defect (adjusted odds ratio = 3.06; 95% confidence interval = 1.07-8.79). In the exploratory analysis, an elevated odds ratio was detected for 1 congenital heart defect, single ventricle. CONCLUSIONS: We observed relationships between maternal periconceptional butalbital use and certain congenital heart defects. These associations have not been reported before, and some may be spurious. Butalbital use was rare and despite the large size of the National Birth Defects Prevention Study, the number of exposed case and control infants was small. However, if confirmed in additional studies, our findings will be useful in weighing the risks and benefits of butalbital for the treatment of migraine and tension-type headaches.

Risks and safety of pandemic H1N1 influenza vaccine in pregnancy: exposure prevalence, preterm delivery, and specific birth defects.

UNLABELLED: We estimated exposure prevalence and studied potential risks for preterm delivery (PTD) and specific birth defects associated with exposure to the unadjuvanted pH1N1-containing vaccines in the 2009-2010 and 2010-2011 influenza seasons. We used data from 4 regional centers in the United States collected as part of the Slone Epidemiology Center's Birth Defects Study. For PTD, propensity score-adjusted time-varying hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for exposure anytime in pregnancy and for each trimester. For 41 specific major birth defects, propensity score-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. Among 4191 subjects, there were 3104 mothers of malformed (cases) and 1087 mothers of nonmalformed (controls). Exposure prevalences among controls were 47% for the 2009-2010 season and 38% for the 2010-2011 season; prevalence varied by geographic region. Results for PTD differed between the two seasons, with risks above and below the null for the 2009-2010 and 2010-2011 seasons, respectively. For 41 specific birth defects, most adjusted ORs were close to 1.0. Three defects had adjusted ORs>2.0 and four had risks<0.5; however, 95% CIs for these were wide. CONCLUSIONS: Among women exposed to pH1N1 vaccine, we found a decreased risk for PTD in the 2010-2011 season; risk was increased in 2009-2010, particularly following exposure in the first trimester, though the decrease in gestational length was less than 2 days. For specific major defects, we found no meaningful evidence of increased risk for specific congenital malformations following pH1N1 influenza vaccinations in the 2009-2010 and 2010-2011 seasons.

Risks and safety of pandemic H1N1 influenza vaccine in pregnancy: birth defects, spontaneous abortion, preterm delivery, and small for gestational age infants.

INTRODUCTION: There is a need for additional information on the fetal risks and relative safety of the pandemic H1N1 monovalent or trivalent influenza (pH1N1)-containing vaccines in women exposed during pregnancy. METHODS: To assess risks and relative safety of the pH1N1-containing vaccines, we conducted a prospective cohort study of pH1N1-vaccine-exposed and unexposed comparison women residing in the U.S. or Canada who were recruited during pregnancy and followed to outcome between October 2009 and August 2012. For exposure to the pH1N1 vaccine, adjusted relative risks (RRs) and 95% confidence intervals (CIs) were estimated for major birth defects and infants small for gestational age. Adjusted hazard ratios (HRs) and 95% CIs were estimated for spontaneous abortion and preterm delivery for time-varying exposure. RESULTS: There were 1032 subjects available for analysis; 841 women were exposed to a pH1N1-containing vaccine in pregnancy, and 191 women were unexposed to any influenza vaccine in pregnancy. Nine of 328 (2.7%) first-trimester-exposed pregnancies resulted in an infant with a major birth defect compared to 6/188 (3.2%) in the unexposed (adjusted RR 0.79, 95% CI 0.26-2.42). The HR for spontaneous abortion was not elevated (adjusted HR 0.92, 95% CI 0.31-2.72). Adjusted HRs for preterm delivery were elevated for exposure anytime in pregnancy (3.28, 95% CI 1.25-8.63), specifically with exposure in the 1st or 2nd trimester. However, the mean decrease in gestational age in the exposed pregnancies was approximately three days. Adjusted RRs for small for gestational age infants on weight and length approximated 1.0. CONCLUSIONS: For the 2009-12 influenza seasons combined, we found no meaningful evidence of increased RR or HR for major birth defects, spontaneous abortion, or small for gestational age infants. There was some evidence of an increased HR for preterm delivery following pH1N1-influenza vaccine exposure; however the decrease in gestational age on average was approximately three days.

Influenza vaccine safety in pregnancy: can we identify exposures?

PURPOSE: To assess the feasibility of identifying influenza vaccine exposure in pregnancy. METHODS: Two study designs were used. (i) Women who contacted the Organization of Teratology Information Specialists (OTIS) network and were referred to their research center or contacted the center directly were invited to participate. (ii) Vaccine exposure information was gathered within an ongoing case-control surveillance program, the Slone Birth Defects Study (BDS). To confirm vaccine exposure and obtain details (e.g., brand name, presence of thimerosal), we requested medical records. If records were not available, we contacted the provider for information regarding the vaccine product used in that setting. If the provider used only one vaccine product during the reported exposure period, we assumed those vaccine details applied to the reported exposure. Otherwise, no details could be inferred. RESULTS: Between September 2006 and February 2008, OTIS enrolled 106 women who reported influenza vaccine exposure during pregnancy. Vaccine was confirmed for 100 (94.3%); brand was confirmed for 87 (82.1%). Among 2177 BDS interviews completed during the same period, 462 (20.8%) reported influenza vaccine exposure; brand and formulation were available for 314 (69.5%). Over one quarter of the BDS women (29%) received their vaccine in nontraditional settings, where influenza vaccine exposure would not likely be recorded in their medical record. CONCLUSIONS: We demonstrated the capacity both to identify influenza vaccine exposure in pregnancy and to obtain important details of the specific vaccine administered. Many women receive influenza vaccines outside of typical health care settings, which has important implications for influenza vaccine studies that rely on medical records.

Nonsteroidal antiinflammatory drugs in late pregnancy and persistent pulmonary hypertension of the newborn.

OBJECTIVE: Persistent pulmonary hypertension of the newborn (PPHN) is a clinical syndrome of late-preterm and full-term infants associated with failure of the normal fetal-to-neonatal circulatory transition. This study was designed to test the hypothesis that risk for PPHN is increased after antenatal exposure to nonsteroidal antiinflammatory drugs (NSAIDs), with particular emphasis on late gestational exposures. METHODS: Between 1998 and 2003, we interviewed 377 women whose infants had PPHN and 836 control mothers of infants matched to cases by hospital and birth date. Interviews captured information on prescription and over-the-counter medication use in pregnancy as well as a variety of potential confounding factors. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for third-trimester maternal NSAID use were estimated by using multivariate conditional logistic regression. RESULTS: During the third trimester of gestation, 33 infants (8.8%) with PPHN were exposed to any NSAID compared with 80 (9.6%) controls (OR 0.8; 95% CI 0.5-1.3). We observed an elevated OR for PPHN risk among infants whose mothers consumed aspirin during the third-trimester; however, the lower 95% CI included the null. Neither nonaspirin NSAIDs at any time during pregnancy nor ibuprofen use during the third trimester was associated with an elevated risk of PPHN. Similarly, no association was observed between a mother's third-trimester acetaminophen use and the occurrence of PPHN in her newborn. CONCLUSIONS: This large multicenter epidemiologic study of PPHN risk revealed no evidence to support the hypothesis that maternal consumption during pregnancy of NSAIDs overall or ibuprofen in particular is associated with PPHN risk.

Safety of macrolides during pregnancy.

OBJECTIVE: Prior studies have reported increased risks of congenital heart defects (CHD) and pyloric stenosis (PS) after prenatal exposure to macrolide antibiotics. We sought to assess the association between maternal use of erythromycin and nonerythromycin macrolides and the risks of CHD and PS. STUDY DESIGN: Among participants in the Slone Epidemiology Center Birth Defects Study from 1994 through 2008, we identified 4132 infants with CHD and 735 with PS as cases, and 6952 infants without any malformation as controls. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of erythromycin or nonerythromycin macrolides in each trimester using conditional logistic regression and adjusting for risk factors for CHD and PS, fever, specific types of infections, and their associated treatments. RESULTS: During the first trimester, 0.4% and 0.7% of control women had used erythromycin and nonerythromycin macrolides, respectively. Compared to non-use during pregnancy, first-trimester exposure to erythromycin was not associated with an increased risk of CHD (OR, 1.3; 95% CI, 0.6-2.6) or PS (OR, 0.9; 95% CI, 0.3-3.0). The corresponding ORs for nonerythromycin macrolides were 0.7 (95% CI, 0.4-1.3) for CHD and 1.7 (95% CI, 0.6-4.6) for PS. We found no association between third-trimester exposure to erythromycin or nonerythromycin macrolides and the risk of PS. Hypothesis generation analyses did not identify appreciable associations between maternal use of macrolides and other common specific birth defects. CONCLUSION: We found no meaningful associations between the risks of CHD, PS, and other common malformations in relation to use of macrolides in pregnancy.

Correcting for exposure misclassification using survival analysis with a time-varying exposure.

PURPOSE: Survival analysis is increasingly being used in perinatal epidemiology to assess time-varying risk factors for various pregnancy outcomes. Here we show how quantitative correction for exposure misclassification can be applied to a Cox regression model with a time-varying dichotomous exposure. METHODS: We evaluated influenza vaccination during pregnancy in relation to preterm birth among 2267 non-malformed infants whose mothers were interviewed as part of the Slone Birth Defects Study during 2006 through 2011. The hazard of preterm birth was modeled using a time-varying exposure Cox regression model with gestational age as the time-scale. The effect of exposure misclassification was then modeled using a probabilistic bias analysis that incorporated vaccination date assignment. The parameters for the bias analysis were derived from both internal and external validation data. RESULTS: Correction for misclassification of prenatal influenza vaccination resulted in an adjusted hazard ratio (AHR) slightly higher and less precise than the conventional analysis: Bias-corrected AHR 1.04 (95% simulation interval, 0.70-1.52); conventional AHR, 1.00 (95% confidence interval, 0.71-1.41). CONCLUSIONS: Probabilistic bias analysis allows epidemiologists to assess quantitatively the possible confounder-adjusted effect of misclassification of a time-varying exposure, in contrast with a speculative approach to understanding information bias.

Maternal exposure to amoxicillin and the risk of oral clefts.

BACKGROUND: Prior studies have suggested an increased risk of oral clefts after exposure to amoxicillin in early pregnancy, but findings have been inconsistent. METHODS: Among participants in the Slone Epidemiology Center Birth Defects Study from 1994 to 2008, we identified 877 infants with cleft lip with/without cleft palate and 471 with cleft palate alone. Controls included 6952 nonmalformed infants. Mothers were interviewed about demographic, reproductive and medical factors, and details of medication use. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of amoxicillin in the first trimester using conditional logistic regression and adjusting for known risk factors for oral clefts, as well as for infections, fever, and concomitant treatments. RESULTS: In the control group, 2.1% of women had used amoxicillin in the first trimester. Maternal use of amoxicillin was associated with an increased risk of cleft lip with/without cleft palate (adjusted OR = 2.0 [95% confidence interval = 1.0-4.1]), with an OR of 4.3 (1.4-13.0) for third-gestational-month use. Risks were not elevated for use of other penicillins or cephalosporins. For cleft palate, the OR for first-trimester amoxicillin was 1.0 (0.4-2.3) with an OR of 7.1 (1.4-36) for third-gestational month use. CONCLUSIONS: Amoxicillin use in early pregnancy may be associated with an increased risk of oral clefts.

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.

Drug certainty-response in interview-based studies.

PURPOSE: Imperfect recall of exposure timing challenges the ascertainment of medications in interview-based studies. METHODS: We propose an algorithm to classify medication exposure, taking into account recall certainty. The availability of medication use details, including duration of use, start and stop dates, and maternal estimates of how certain they were about these dates, allowed classification of subjects as either likely or possibly exposed in the first trimester of pregnancy. We applied the algorithm to study an association between prenatal tetracycline exposure and risk of congenital heart defects previously reported by the National Birth Defects Prevention Study, using 1993-2008 data from 11,517 subjects in the Slone Epidemiology Center Birth Defects Study. RESULTS: Among women exposed to tetracyclines during pregnancy (n = 58), 50% and 19% were likely and possibly exposed, respectively, in the first trimester, and 31% were exposed outside the first trimester. Compared with non-use during pregnancy, the crude OR for exposure outside the first trimester was 1.0 (95%CI 0.4-2.5), and that for exposed (likely or possibly, combined) in the first trimester was 1.7 (95%CI 0.9-3.2); however, the ORs based on the algorithms were 0.9 (95%CI 0.3-3.0) for possibly exposed and 2.2 (95%CI 1.0-4.6) for likely exposed. CONCLUSIONS: A "certainty-response" (stronger association with higher level of certainty) was found within exposures in the window of etiological interest. Algorithms for exposure classification that incorporate recall certainty may be useful in interview-based studies.