Canary in the Coal Mine? Male Infertility as a Marker of Overall Health.

Male factor infertility is a common problem. Evidence is emerging regarding the spectrum of systemic disease and illness harbored by infertile men who otherwise appear healthy. In this review, we present evidence that infertile men have poor overall health and increased morbidity and mortality, increased rates of both genitourinary and non-genitourinary malignancy, and greater risks of systemic disease. The review also highlights numerous genetic conditions associated with male infertility as well as emerging translational evidence of genitourinary birth defects and their impact on male infertility. Finally, parallels to the overall health of infertile women are presented. This review highlights the importance of a comprehensive health evaluation of men who present for an infertility assessment.

Disruption of DNA methylation-mediated cranial neural crest proliferation and differentiation causes orofacial clefts in mice.

Orofacial clefts of the lip and palate are widely recognized to result from complex gene-environment interactions, but inadequate understanding of environmental risk factors has stymied development of prevention strategies. We interrogated the role of DNA methylation, an environmentally malleable epigenetic mechanism, in orofacial development. Expression of the key DNA methyltransferase enzyme DNMT1 was detected throughout palate morphogenesis in the epithelium and underlying cranial neural crest cell (cNCC) mesenchyme, a highly proliferative multipotent stem cell population that forms orofacial connective tissue. Genetic and pharmacologic manipulations of DNMT activity were then applied to define the tissue- and timing-dependent requirement of DNA methylation in orofacial development. cNCC-specific Dnmt1 inactivation targeting initial palate outgrowth resulted in OFCs, while later targeting during palatal shelf elevation and elongation did not. Conditional Dnmt1 deletion reduced cNCC proliferation and subsequent differentiation trajectory, resulting in attenuated outgrowth of the palatal shelves and altered development of cNCC-derived skeletal elements. Finally, we found that the cellular mechanisms of cleft pathogenesis observed in vivo can be recapitulated by pharmacologically reducing DNA methylation in multipotent cNCCs cultured in vitro. These findings demonstrate that DNA methylation is a crucial epigenetic regulator of cNCC biology, define a critical period of development in which its disruption directly causes OFCs, and provide opportunities to identify environmental influences that contribute to OFC risk.

The fetal lineage is susceptible to Zika virus infection within days of fertilization.

Adults contracting Zika virus (ZIKV) typically exhibit mild symptoms, yet ZIKV infection of pregnant individuals can cause miscarriage or birth defects in their offspring. Many studies have focused on maternal-to-fetal ZIKV transmission via blood and placenta. Notably, however, ZIKV is also transmitted sexually, raising the possibility that ZIKV could infect the embryo shortly after fertilization, long before the placenta is established. Here, we evaluate the consequences of ZIKV infection in mouse embryos during the first few days of embryogenesis. We show that divergent strains of ZIKV can infect the fetal lineage and can cause developmental arrest, raising concern for the developmental consequences of sexual ZIKV transmission. This article has an associated 'The people behind the papers' interview.

Statistical methods for assessing the effects of de novo variants on birth defects.

With the development of next-generation sequencing technology, de novo variants (DNVs) with deleterious effects can be identified and investigated for their effects on birth defects such as congenital heart disease (CHD). However, statistical power is still limited for such studies because of the small sample size due to the high cost of recruiting and sequencing samples and the low occurrence of DNVs. DNV analysis is further complicated by genetic heterogeneity across diseased individuals. Therefore, it is critical to jointly analyze DNVs with other types of genomic/biological information to improve statistical power to identify genes associated with birth defects. In this review, we discuss the general workflow, recent developments in statistical methods, and future directions for DNV analysis.

Actin cytoskeletal regulation of ciliogenesis in development and disease.

Primary cilia are antenna-like sensory organelles that are evolutionarily conserved in nearly all modern eukaryotes, from the single-celled green alga, Chlamydomonas reinhardtii, to vertebrates and mammals. Cilia are microtubule-based cellular projections that have adapted to perform a broad range of species-specific functions, from cell motility to detection of light and the transduction of extracellular mechanical and chemical signals. These functions render cilia essential for organismal development and survival. The high conservation of cilia has allowed for discoveries in C. reinhardtii to inform our understanding of the basic biology of mammalian primary cilia, and to provide insight into the genetic etiology of ciliopathies. Over the last two decades, a growing number of studies has revealed that multiple aspects of ciliary homeostasis are regulated by the actin cytoskeleton, including centrosome migration and positioning, vesicle transport to the basal body, ectocytosis, and ciliary-mediated signaling. Here, we review actin regulation of ciliary homeostasis, and highlight conserved and divergent mechanisms in C. reinhardtii and mammalian cells. Further, we compare the disease manifestations of patients with ciliopathies to those with mutations in actin and actin-associated genes, and propose that primary cilia defects caused by genetic alteration of the actin cytoskeleton may underlie certain birth defects.

Safety Data Timelines for Pregnant Individuals with HIV on Antiretroviral Therapy.

Antiretrovirals are often approved by the Food and Drug Administration without sufficient safety data regarding their use in pregnancy. To quantify this delay, we calculated the interval from the approval date to their inclusion in the Antiretroviral Pregnancy Registry prospective analysis (≥ 200 first trimester exposures); median delay was six years.

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.

Real World Data are Not Always Big Data: The Case for Primary Data Collection on Medication Use in Pregnancy in the Context of Birth Defects Research.

Many examples of the use of real-world data in the area of pharmacoepidemiology include "big data" such as insurance claims, medical records, or hospital discharge databases. However, "big" is not always better, particularly when studying outcomes with narrow windows of etiologic relevance. Birth defects are one such outcome, where specificity of exposure timing is critical. Studies with primary data collection can be designed to query details on the timing of medication use, as well as type, dose, frequency, duration, and indication, that can better characterize the "real world". Because birth defects are rare, etiologic studies are typically case-control in design, like the National Birth Defects Prevention Study, Birth Defects Study to Evaluate Pregnancy exposureS, and Slone Birth Defects Study. Recall bias can be a concern, but the ability to collect detailed information on both prescription and over-the-counter medication use and on other exposures such as diet, family history, and sociodemographic factors is a distinct advantage over claims and medical record data sources. Case-control studies with primary data collection are essential to advancing the pharmacoepidemiology of birth defects.

Gene-teratogen interactions influence the penetrance of birth defects by altering Hedgehog signaling strength.

Birth defects result from interactions between genetic and environmental factors, but the mechanisms remain poorly understood. We find that mutations and teratogens interact in predictable ways to cause birth defects by changing target cell sensitivity to Hedgehog (Hh) ligands. These interactions converge on a membrane protein complex, the MMM complex, that promotes degradation of the Hh transducer Smoothened (SMO). Deficiency of the MMM component MOSMO results in elevated SMO and increased Hh signaling, causing multiple birth defects. In utero exposure to a teratogen that directly inhibits SMO reduces the penetrance and expressivity of birth defects in Mosmo-/- embryos. Additionally, tissues that develop normally in Mosmo-/- embryos are refractory to the teratogen. Thus, changes in the abundance of the protein target of a teratogen can change birth defect outcomes by quantitative shifts in Hh signaling. Consequently, small molecules that re-calibrate signaling strength could be harnessed to rescue structural birth defects.

Three-Year Post-Neonatal Intensive Care Unit Health Care Utilization Among Infants with Congenital Anomalies.

OBJECTIVE: To describe 3-year post-neonatal intensive care unit (NICU) health care use among children with congenital anomalies discharged home from a level IV NICU. STUDY DESIGN: Retrospective chart review of children with congenital anomalies enrolled in a previous prospective cohort study from 201 to 2020. We assessed hospital readmission rate, number of surgeries, and durable medical equipment (DME) use by type of anomaly. RESULTS: Among 166 infants enrolled in the original study, 158 survived to NICU discharge. One-third of the cohort had a genetic anomaly. Six of 158 patients (4%) died before 3 years of age. More than one-half the children were readmitted within the first 2 years of life, and one-third were readmitted in the third year of life. Readmissions were greatest for those with multiple, musculoskeletal, and central nervous system anomalies and lowest for abdominal-wall defects. Approximately one-half the children underwent surgeries, and this proportion remained constant over the 3-year time. Sixty-two percent of patients received DME at discharge, with gastrostomy tubes being the most common. Gastrostomy tubes were still present in 75% of the patients at 3 years of age. CONCLUSION: Children with congenital anomalies are at risk for increased health care use during early childhood. Those with multiple anomalies, a genetic syndrome, musculoskeletal, and central nervous system anomalies and those discharged with DME are at greatest risk whereas those with abdominal-wall defects are at lowest risk. Provider awareness, high-quality discharge training, parent psychological support, greater assimilation of families in the NICU, and telehealth may be some strategies to better support these families.

Classification of isolated versus multiple birth defects: An automated process for population-based registries.

Epidemiologic studies of birth defects often conduct separate analyses for cases that have isolated defects (e.g., spina bifida only) and cases that have multiple defects (e.g., spina bifida and a congenital heart defect). However, in some instances, cases with additional defects (e.g., spina bifida and clubfoot) may be more appropriately considered as isolated because the co-occurring defect (clubfoot) is believed to be developmentally related to the defect of interest. Determining which combinations should be considered isolated can be challenging and potentially resource intensive for registries. Thus, we developed automated classification procedures for differentiating between isolated versus multiple defects, while accounting for developmentally related defects, and applied the approach to data from the Texas Birth Defects Registry (1999-2018 deliveries). Among 235,544 nonsyndromic cases in Texas, 89% of cases were classified as having isolated defects, with proportions ranging from 25% to 92% across 43 specific defects analyzed. A large proportion of isolated cases with spina bifida (44%), lower limb reduction defects (44%), and holoprosencephaly (32%) had developmentally related defects. Overall, our findings strongly support the need to account for isolated versus multiple defects in risk factor association analyses and to account for developmentally related defects when doing so, which has implications for interpreting prior studies.

Antiepileptic treatment with levetiracetam during the first trimester and pregnancy outcome: An observational study.

OBJECTIVE: Levetiracetam is increasingly used in pregnant women with epilepsy. Although teratogenic effects have not been observed so far, data on the risks of spontaneous abortion and major birth defects are still limited, especially for the frequently used dual therapy of levetiracetam and lamotrigine. Our primary aim was to analyze rates of major birth defects and spontaneous abortion after maternal levetiracetam treatment. METHODS: This was a cohort study based on pregnancies recorded by the Embryotox Center from 2000 to 2017. Outcomes of prospectively ascertained pregnancies with first trimester levetiracetam monotherapy (n = 221) were compared to pregnancies with lamotrigine monotherapy for epilepsy (n = 469). In addition, all pregnancies with levetiracetam (n = 364) exposure during the first trimester were analyzed in comparison to a nonexposed cohort (n = 729). Pregnancies with the most frequently used combination therapy comprising levetiracetam and lamotrigine (n = 80) were evaluated separately. RESULTS: There was no significantly increased risk of major birth defects or of spontaneous abortions after first trimester exposure to levetiracetam. Birth weight of male neonates was significantly lower after levetiracetam monotherapy compared to lamotrigine monotherapy. Dual therapy with levetiracetam and lamotrigine resulted in a significantly increased risk of spontaneous abortion (adjusted hazard ratio = 3.01, 95% confidence interval [CI] = 1.43-6.33) and a nonsignificant effect estimate for major birth defects (7.7%, n = 5/65, adjusted odds ratio = 1.47, 95% CI = .48-4.47) compared to a nonexposed cohort. SIGNIFICANCE: Our study confirms the use of levetiracetam as a suitable antiepileptic drug in pregnancy. The lower birth weight of male neonates after maternal levetiracetam monotherapy and the unexpectedly high risk of spontaneous abortion and birth defects after dual therapy with levetiracetam and lamotrigine require further investigation.

Maternal exposure to zolpidem and risk of specific birth defects.

Zolpidem is a non-benzodiazepine agent indicated for treatment of insomnia. While zolpidem crosses the placenta, little is known about its safety in pregnancy. We assessed associations between self-reported zolpidem use 1 month before pregnancy through to the end of the third month ("early pregnancy") and specific birth defects using data from two multi-site case-control studies: National Birth Defects Prevention Study and Slone Epidemiology Center Birth Defects Study. Analysis included 39,711 birth defect cases and 23,035 controls without a birth defect. For defects with ≥ 5 exposed cases, we used logistic regression with Firth's penalised likelihood to estimate adjusted odds ratios and 95% confidence intervals, considering age at delivery, race/ethnicity, education, body mass index, parity, early-pregnancy antipsychotic, anxiolytic, antidepressant use, early-pregnancy opioid use, early-pregnancy smoking, and study as potential covariates. For defects with three-four exposed cases, we estimated crude odds ratios and 95% confidence intervals. Additionally, we explored differences in odds ratios using propensity score-adjustment and conducted a probabilistic bias analysis of exposure misclassification. Overall, 84 (0.2%) cases and 46 (0.2%) controls reported early-pregnancy zolpidem use. Seven defects had sufficient sample size to calculate adjusted odds ratios, which ranged from 0.76 for cleft lip to 2.18 for gastroschisis. Four defects had odds ratios > 1.8. All confidence intervals included the null. Zolpidem use was rare. We could not calculate adjusted odds ratios for most defects and estimates are imprecise. Results do not support a large increase in risk, but smaller increases in risk for certain defects cannot be ruled out.

Associations between maternal periconceptional alcohol consumption and risk of omphalocele among offspring, National Birth Defects Prevention Study, 1997-2011.

OBJECTIVE: Previous studies of alcohol consumption during pregnancy and omphalocele have produced mixed results. We updated an earlier analysis of National Birth Defects Prevention Study (NBDPS) data, adding six years of participants, to examine associations between maternal alcohol consumption and omphalocele. METHODS: NBDPS was a multi-site, population-based case-control study in the United States. Cases were identified from birth defect surveillance programs in 10 states; controls were liveborn infants without a birth defect randomly selected from the same catchment areas. Mothers self-reported alcohol consumption during the periconceptional period (one month before through the third gestational month) via telephone interview. Our study included mothers of 410 omphalocele cases and 11,219 controls with estimated dates of delivery (EDDs) during 1997-2011. We used logistic regression to estimate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for periconceptional alcohol consumption and omphalocele. We performed a probabilistic bias analysis to evaluate the impact of alcohol exposure misclassification on our results. RESULTS: Overall, 44% of case and 38% of control mothers reported periconceptional alcohol consumption; 22% and 17%, respectively, reported binge drinking. Any maternal periconceptional alcohol consumption was associated with modestly increased odds of omphalocele (AOR 1.35, 95% CI 1.09, 1.68), as was binge drinking (AOR 1.47, 95% CI 1.08, 2.01). Our bias analysis yielded estimates further from the null. CONCLUSIONS: We observed modest associations between maternal periconceptional alcohol consumption and omphalocele. Based on our bias analysis, studies of alcohol and birth defects not accounting for exposure misclassification may underestimate associations.

Birth defects among offspring of California firefighters, 2007-2019.

PURPOSE: Limited research examines birth defects from maternal or paternal firefighting exposure. This study aims to assess if maternal or paternal occupational exposure to firefighting during periconception is associated with offspring birth defects. METHODS: Data from California birth certificates (2007-2019) were linked to maternal / offspring hospitalization records. Occupation during the periconceptional period was categorized from vital statistics as the following: paternal non-firefighting (n = 4,135,849), paternal firefighting (n = 22,732), maternal non-firefighting (n = 3,332,255) and maternal firefighting (n = 502). Birth defects were identified using ICD codes, grouped by anatomical regions. Adjusted odds ratios were estimated, and sensitivity analyses explored police officer reference groups and detailed birth defect categories. RESULTS: Offspring of paternal firefighters had lower odds of circulatory defects (aOR = 0.9, 95% CI 0.8, 1.0), oral clefts (aOR = 0.6, 95% CI 0.4, 0.8) and respiratory defects (0.7, 95% CI 0.6, 0.9) compared to paternal non-firefighters. Associations between maternal firefighting and offspring birth defects were imprecise. Substituting police officers as the reference group attenuated findings. CONCLUSIONS: Offspring of paternal firefighters may have similar or slightly lower birth defect odds compared to offspring of non-firefighters. Limited data was available for assessing maternal firefighting outcomes. Future studies should prioritize studies using occupational exposure matrices to limit misclassification of exposure.

Academic achievement at ages 11 and 16 in children born with congenital anomalies in England: A multi-registry linked cohort study.

BACKGROUND: Children born with major congenital anomalies (CAs) have lower academic achievement compared with their peers, but the existing evidence is restricted to a number of specific CAs. OBJECTIVES: To investigate academic outcomes at ages 11 and 16 in children with major isolated structural CAs and children with Down or Turner syndromes. METHODS: This population-based cohort study linked data on approximately 11,000 school-aged children born with major CAs in 1994-2004 registered by four regional CA registries in England with education data from the National Pupil Database (NPD). The comparison group was a random sample of children without major CAs from the background population recorded in the NPD that were frequency matched (5:1) to children with CAs by birth year, sex and geographical area. RESULTS: Overall, 71.9%, 73.0% and 80.9% of children with isolated structural CAs achieved the expected attainment level at age 11 compared to 78.3%, 80.6% and 86.7% of the comparison group in English language, Mathematics and Science, respectively. Children with nervous system CAs as a whole had the lowest proportion who achieved the expected attainment at age 11. At age 16, 46.9% of children with CAs achieved the expected level compared to 52.5% of their peers. Major CAs were associated with being up to 9% (95% confidence interval [CI] 8%, 11%) and 12% (95% CI 9%, 14%) less likely to achieve expected levels at ages 11 and 16, respectively, after adjustment for socioeconomic deprivation. CONCLUSIONS: Although many children with isolated CAs achieved the expected academic level at ages 11 and 16, they were at higher risk of underachievement compared to their peers. These stark yet cautiously encouraging results are important for counselling parents of children with specific CAs and also highlight the possible need for special education support to reduce potential academic difficulties.

Role of non-chromosomal birth defects on the risk of developing childhood Hodgkin lymphoma: A Children's Oncology Group study.

BACKGROUND: Non-chromosomal birth defects are an important risk factor for several childhood cancers. However, these associations are less clear for Hodgkin lymphoma (HL). Therefore, we sought to more fully elucidate the association between non-chromosomal birth defects and HL risk. PROCEDURE: Information on cases (n = 517) diagnosed with HL (ages of 0-14) at Children's Oncology Group Institutions for the period of 1989-2003 was obtained. Control children without a history of cancer (n = 784) were identified using random digit dialing and individually matched to cases on sex, race/ethnicity, age, and geographic location. Parents completed comprehensive interviews and answered questions including whether their child had been born with a non-chromosomal birth defect. To test the association between birth defects and HL risk, conditional logistic regression was applied to generate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). RESULTS: Children born with any non-chromosomal birth defect were not more likely to be diagnosed with HL at 0-14 years of age (aOR: 0.91; 95% CI: 0.69-1.21). No associations were detected between major or minor birth defects and HL (aOR: 1.34; 95% CI: 0.67-2.67 and aOR: 0.88; 95% CI: 0.57-1.34, respectively). Similarly, no association was observed for children born with any birth defect and EBV-positive HL (aOR: 0.57; 95% CI: 0.25-1.26). CONCLUSIONS: Previous assessments of HL in children with non-chromosomal birth defects have been limited. Using data from the largest case-control study of HL in those <15 years of age, we did not observe strong associations between being born with a birth defect and HL risk.

Congenital anomalies during Covid-19: artifact of surveillance or a real TORCH?

Infections in the first trimester of pregnancy can be teratogenic, but the possibility that Covid-19 could lead to birth defects is unclear. We examined whether SARS-CoV-2 infection during pregnancy or exposure to pandemic conditions were associated with the risk of congenital anomalies. We carried out a retrospective study of 420,222 neonates born in Quebec, Canada in two time periods: prepandemic (January 1, 2017 to March 12, 2020) vs. pandemic (March 13, 2020 to March 31, 2022). We classified pandemic births as early (first trimester completed before the pandemic) or late (first trimester during the pandemic), and identified patients with SARS-CoV-2 infections during pregnancy. We applied (1) adjusted log-binomial regression models to assess the association between SARS-CoV-2 infection and congenital anomalies, and (2) autoregressive interrupted time series regression to analyze temporal trends in the monthly number of defects in all patients regardless of infection. In total, 29,263 newborns (7.0%) had a congenital anomaly. First trimester SARS-CoV-2 infections were not associated with a greater risk of birth defects compared with no infection (RR 1.07, 95% CI 0.59-1.95). However, births during the late pandemic period were more likely to be diagnosed with congenital microcephaly compared with prepandemic births (RR 1.44, 95% CI 1.21-1.71). Interrupted time series analysis confirmed that the frequency of microcephaly increased during the late pandemic period, whereas other anomalies did not. We conclude that Covid-19 is likely not teratogenic, but enhanced surveillance of anomalies among late pandemic births may have heightened the detection of infants with microcephaly.

A multidisciplinary and structured investigation of three suspected clusters of transverse upper limb reduction defects in France.

INTRODUCTION: Between 2019-2021, facing public concern, a scientific expert committee (SEC) reanalysed suspected clusters of transverse upper limb reduction defects (TULRD) in three administrative areas in France, where initial investigations had not identified any risk exposure. We share here the national approach we developed for managing suspicious clusters of the same group of congenital anomalies occurring in several areas. METHODS: The SEC analysed the medical records of TURLD suspected cases and performed spatiotemporal analyses on confirmed cases. If the cluster was statistically significant and included at least three cases, the SEC reviewed exposures obtained from questionnaires, environmental databases, and a survey among farmers living near to cases' homes concerning their plant product use. RESULTS: After case re-ascertainment, no statistically significant cluster was observed in the first administrative areas. In the second area, a cluster of four children born in two nearby towns over two years was confirmed, but as with the initial investigations, no exposure to a known risk factor explaining the number of cases in excess was identified. In the third area, a cluster including just two cases born the same year in the same town was confirmed. DISCUSSION: Our experience highlights that in the event of suspicious clusters occurring in different areas of a country, a coordinated and standardised approach should be preferred.

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.