0202 Later Sleep Onset Timing Predicts Greater Postpartum Weight Retention at One Year Postpartum

Abstract Introduction Postpartum weight retention (PPWR), defined as ≥5kg difference between pre-pregnancy and 12-month postpartum weights, is associated with sustained weight retention across the life course. Maternal insufficient sleep duration is associated with PPWR. However, few studies have measured sleep objectively and other potentially relevant sleep dimensions. Moreover, little is known about these associations in the first month postpartum, the period with the greatest maternal sleep disruption. We investigated whether nocturnal total sleep time (TST), wake after sleep onset (WASO), and sleep onset time, predicted PPWR among mothers with full-term infants. Methods This study is a preliminary, secondary analysis of a subsample of mothers from the Snuggle Bug study (n=51, age M±SD= 32.2±5.2y, 35.3% Hispanic/Latina), a longitudinal cohort of mother-infant dyads with infants of normal birth weight. Sleep in mothers was measured using wrist-actigraphy and sleep logs over five days at three weeks postpartum. Pre-pregnancy weight and post-delivery weight were self-reported at three weeks postpartum and gestational weight gain (GWG) was computed. At 12 months postpartum, maternal weight was measured twice using an electronic digital scale (nearest 0.1kg), and breastfeeding duration was reported. Linear and binary logistic, multiple regression models examined the associations of each sleep metric with change in maternal weight (pre-pregnancy to 12-month postpartum) and PPWR status (≥5kg difference), respectively, adjusting for age, pre-pregnancy weight, GWG, and breastfeeding duration, and in the models with WASO and sleep onset, TST was added. Results At 3 weeks postpartum, mothers’ mean TST, WASO, and sleep onset were 354.0±65.0min, 146.3±50.3min, and 23:19±1:23, respectively. The mean weight change from pre-pregnancy to 12 months postpartum was 3.0±6.8kg (5.0±8.7% increase from pre-pregnancy weight), and 34.0% had PPWR. Age and breastfeeding duration were not associated with the outcomes and were dropped from the models. Each one-hour delay in sleep onset predicted greater weight change (ΔR2=0.08, B=1.71kg, β=0.35, p=0.03), and greater odds of PPWR (OR: 1.90, 95%CI: 1.01-3.55, p=0.045). TST and WASO were not associated with the outcomes. Conclusion Among mothers, later bedtimes during early postpartum, independent of sleep duration, may heighten the risk for PPWR at one-year postpartum, which may have significant implications for cardiometabolic outcomes later in life. Support (if any) NIH/NHLBI R01HL147931