724: Interpregnancy BMI changes and offspring mortality following second pregnancy

Abstract

Obesity in pregnancy is associated with increased risk of neonatal mortality, however the effect of interpregnancy weight change is less understood. We sought to understand the impact of maternal interpregnancy body mass index (BMI) change on second offspring mortality risk. We included 266,971 women with first and second singleton deliveries between 1989 and 2015 from the Utah Population Database. Our exposure was defined as interpregnancy BMI change from date of first delivery to conception date of second pregnancy, derived from best clinical gestational dating of second pregnancy. We categorized exposure as: <-1, [-1, 0], [0, <1 reference], [1, 2], [2-4], ≥4 BMI units (kg/m2). Our outcomes were all-cause age-specific mortality: neonatal (≤ 28 days), infant (≤1 year old) childhood (≤5 years old), and late childhood (5-<18 years old). Analyses were based on Cox proportional hazards stratified by full term (>37 weeks) and preterm (< 37 weeks) deliveries. We assessed all-cause mortality and death from congenital anomalies and early infancy. Cox regression was used to estimate hazard ratios of childhood mortality and all models were adjusted for maternal age, race/ethnicity, maternal education, smoking during pregnancy, diabetes, hypertension, assisted reproduction, interpregnancy interval, maternal BMI prior to first pregnancy, infant sex, gestational age (term or not) and small for gestational age. Among full term deliveries, women with BMI change of 4+ had increased risk of neonatal mortality in their second child (hazard ratio 1.63, 95% confidence interval 1.15, 2.31). There were no differences in infant, early or late childhood mortality by interpregnancy BMI change. Maternal interpregnancy BMI changes of 2 to 3.99 and ≥4 had increased risk of all-cause mortality and mortality associated with congenital anomalies or conditions originating in the perinatal period (ICD10 760-779) in their second child (Table 1). In a large U.S. population study, women with large interpregnancy BMI changes have a significant risk of mortality in their second term offspring. Further studies are needed to assess if maternal post-partum weight change are a modifiable risk factor for adverse childhood outcomes.