424: Association between tobacco use and perinatal outcomes in twin gestations

Abstract

OBJECTIVE: To determine whether achievement of body mass index (BMI)-specific weight gain recommendations is associated with a reduced risk of preterm birth (PTB) and improved neonatal outcomes among twin gestations. STUDY DESIGN: A retrospective cohort study of twin gestations delivered at the Medical University of South Carolina from 2000-2010. 588 women who delivered 24 weeks gestation in all prepregnancy BMI categories were included. Women with major fetal anomalies, fetal aneuploidy, twin-twin transfusion syndrome, cotwin fetal demise, and incomplete prenatal weight records were excluded. BMI-specific weight gain recommendations derived from Luke et al, J Reprod Med, 2003 were applied to each woman based on pre-pregnancy BMI. Women were assigned the designation of achieved or underachieved based on total weight gain and gestational age at delivery. Maternal and neonatal outcomes were compared between the groups. Our sample provides 80% power to detect a 50% difference in the rate of PTB < 32 weeks (p<0.05). RESULTS: BMI-specific weight gain goals were achieved by 49.3 % of women. The achieved group had a 2.5 fold reduction in the rate of preterm birth < 32 weeks (13 vs 34%). African Americans, women with an underweight pre-pregnancy BMI and women with a lower number of prenatal visits were significantly less likely to achieve recommended weight gain goals (Table 1). Women who achieved weight gain recommendations were significantly less likely to deliver any twin with a birth weight less than the tenth percentile for gestational age (larger twin, 0.3 vs 4.0 %, smaller twin 10.3 vs 21.5%). Composite neonatal morbidity, days on the respirator, length of hospital stay and rate of neonatal intensive care unit admission were significantly decreased in the achieved group. CONCLUSION: Achievement of BMI specific weight gain recommendations can decrease the incidence of preterm birth < 32 weeks and improve neonatal outcomes in twin gestations.