A retrospective review of the association between maternal body mass index and the risk of congenital anomalies

The objective of the study was to examine the association of congenital anomalies with the specific classes of pre-pregnancy BMI. An IRB-approved retrospective cohort study was performed using the data from the Natality Public Use File from the National Center for Health Statistics (2019). We included all singleton live births and excluded pregnancies with suspected or confirmed chromosomal abnormalities and people with pre-existing diabetes mellitus and missing pertinent data. The primary outcome was the incidence of any major congenital anomalies in liveborn infants. The incidence of anomaly was analyzed across all BMI classes, using individuals with BMI between 18.5 and 24.9 kg/m² as the comparison group. A test of trend was also performed to determine if the risk increased as the BMI class increased. A total of 3 047 382 maternal-neonatal dyads were included in the analysis. A non-significant higher incidence of any major anomaly was noted among people who had underweight and class III BMI. The risk of open neural tube defects, omphalocele, and cleft lip/palate increased and the risk of gastroschisis decreased with an increase in maternal BMI class (p < 0.05). The incidence of congenital anomalies increases as the pre-pregnancy BMI increases. Individuals should be encouraged to optimize their weight prior to conception and if feasible, they should obtain screening for fetal anatomy assessment by a Maternal-Fetal Medicine specialist.