Background Assisted reproductive technology (ART) has been associated with birth defects, but the contributions of multiple births and underlying subfertility remain unclear. We evaluated the effects of subfertility and mediation by multiple births on associations between ART and nonchromosomal birth defects. Methods We identified a retrospective cohort of Massachusetts live births and stillbirths from 2004–2010 among ART-exposed, ART-unexposed subfertile, and fertile mothers using linked information from fertility clinics, vital records, hospital discharges, and birth defects surveillance. Log-binomial regression was used to estimate prevalence ratios and 95% confidence intervals. Mediation analyses were performed to deconstruct the ART-birth defects association into the direct effect of ART, the indirect effect of multiple births, and the effect of ART-multiples interaction. Results Of 17,829 ART-exposed births, 355 had a birth defect, compared with 162 of 9431 births to subfertile mothers and 6183 of 445,080 births to fertile mothers. The adjusted prevalence ratio was 1.5 (95% confidence interval, 1.3–1.6) for ART and 1.3 (1.1–1.5) in subfertile compared with fertile deliveries. We observed elevated rates of several birth defects with ART, including tetralogy of Fallot and hypospadias. Subfertility and multiple births affect these associations, with multiple births explaining 36% of the relative effect of ART on nonchromosomal birth defects. Conclusion Although the risk of birth defects with ART is small, a substantial portion of the relative effect is mediated through multiple births, with subfertility contributing an important role. Future research is needed to determine the impact of newer techniques, such as single embryo transfer, on these risks.

Background/Objectives: In this report, the National Birth Defects Prevention Network (NBDPN) examines and compares gastroschisis and omphalocele for a recent 5-year birth cohort using data from 30 population-based birth defect surveillance programs in the United States. Methods: As a special call for data for the 2019 NBDPN Annual Report, state programs reported expanded data on gastroschisis and omphalocele for birth years 2012–2016. We estimated the overall prevalence (per 10,000 live births) and 95% confidence intervals (CI) for each defect as well as by maternal race/ethnicity, maternal age, infant sex, and case ascertainment methodology utilized by the program (active vs. passive). We also compared distribution of cases by maternal and infant factors and presence/absence of other birth defects. Results: The overall prevalence estimates (per 10,000 live births) were 4.3 (95% CI:4.1–4.4) for gastroschisis and 2.1 (95% CI: 2.0–2.2) for omphalocele. Gastroschisis was more frequent among young mothers (<25 years) and omphalocele more common among older mothers (>40 years). Mothers of infants with gastroschisis were more likely to be underweight/normal weight prior to pregnancy and mothers of infants with omphalocele more likely to be overweight/obese. Omphalocele was twice as likely as gastroschisis to co-occur with other birth defects. Conclusions: This report highlights important differences between gastroschisis and omphalocele. These differences indicate the importance of distinguishing between these defects in epidemiologic assessments. The report also provides additional data on co-occurrence of gastroschisis and omphalocele with other birth defects. This information can provide a basis for future research to better understand these defects.

Background/Objectives: In this data brief, we examine major eye and ear anomalies (anophthalmia/microphthalmia, anotia/microtia, and congenital cataract) for a recent 5-year birth cohort using data from 30 population-based birth defects surveillance programs in the United States. Methods: As a special call for data for the 2018 NBDPN Annual Report, state programs reported expanded data on eye/ear anomalies for birth years 2011–2015. We calculated the combined overall prevalence (per 10,000 live births) and 95% confidence intervals (CI), for the three anomalies as well as by maternal age, maternal race/ethnicity, infant sex, laterality, presence/absence of other major birth defects, and case ascertainment methodology utilized by the program (active vs. passive). Results: The overall prevalence estimate (per 10,000 live births) was 1.5 (95% CI: 1.4–1.5) for anophthalmia/microphthalmia, 1.5 (95% CI: 1.4–1.6) for congenital cataract, and 1.8 (95% CI: 1.7–1.8) for anotia/microtia. Congenital cataract prevalence varied little by maternal race/ethnicity, infant sex, or case ascertainment methodology; prevalence differences were more apparent across strata for anophthalmia/microphthalmia and anotia/microtia. Prevalence among active vs. passive ascertainment programs was 50% higher for anophthalmia/microphthalmia (1.9 vs. 1.2) and two-fold higher for anotia/microtia (2.6 vs. 1.2). Anophthalmia/microphthalmia was more likely than other conditions to co-occur with other birth defects. All conditions were more frequent among older mothers (40+ years). Conclusions: This data brief provides recent prevalence estimates for anophthalmia/microphthalmia, congenital cataract, and anotia/microtia that address a data gap by examining pooled data from 30 population-based surveillance systems, covering a five-year birth cohort of about 12.4 million births.

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).

Background: Risk factors for birth defects are frequently investigated using data limited to liveborn infants. By conditioning on survival, results of such studies may be distorted by selection bias, also described as "livebirth bias." However, the implications of livebirth bias on risk estimation remain poorly understood. Objectives: We sought to quantify livebirth bias and to investigate the conditions under which it arose. Methods: We used data on 3994 birth defects cases and 11 829 controls enrolled in the National Birth Defects Prevention Study to compare odds ratio (OR) estimates of the relationship between three established risk factors (antiepileptic drug use, smoking, and multifetal pregnancy) and four birth defects (anencephaly, spina bifida,