505: Does maternal BMI impact the rate of preterm birth in women receiving 17-OH progesterone?

Abstract

birth in women receiving 17-OH progesterone? Kelly Ruhstaller, Matthew Hoffman, Anthony Sciscione, Nicole Doyle Christiana Care Health System, Obstetrics and Gynecology, Newark, DE OBJECTIVE: To evaluate whether maternal body mass index (BMI) impacts the rate of preterm birth in women receiving 17-OH progesterone caproate (17-OHPC) for a history of preterm delivery. STUDY DESIGN: All patients from the High Risk Clinic who delivered between March 2009 to July 2012 and received 17-OHPC were selected (n 144). Patients were excluded if they did not have a prior preterm birth, had a multifetal gestation, did not receive 17-OHPC prior to 20 weeks, had fetal anomalies or were delivered prior to 37 weeks for an indication other than preterm premature rupture of membranes (n 91). Women who also received a cerclage were included. The primary outcome was spontaneous delivery prior to 37 0/7 weeks. Secondary outcomes were delivery prior to 34 0/7 weeks, delivery prior to 28 0/7 weeks and composite neonatal morbidity (NICU admission, 5-minute APGAR 7 and birthweight 2500g). Women were divided into two groups, BMI 30 (kg/m) and 30 (kg/m). Odds ratios were calculated using BMI 30 as the referent group. RESULTS: In total 35 patients had a BMI 30 and 56 patients had BMI 30 (range 19.5-55.8). Women with a BMI 30 were significantly less likely to deliver prior to 37 0/7 weeks (OR 0.315, 95%CI 0.1280.722) and prior to 34 0/7 weeks (OR 0.282, 95%CI 0.102-0.778) when compared to women with a BMI 30. No significant difference in the rate of delivery prior to 28 0/7 weeks was seen (OR 1.046, 95%CI 0.234-4.68). There was a trend towards lower neonatal morbidity for infants born to women with a BMI 30, however this did not reach significance (OR 0.432, 95%CI 0.182-1.027). CONCLUSION: Obese women receiving 17-OHPC for a history of preterm birth have lower rates of repeat preterm delivery, except very early preterm births ( 28 weeks), compared to their normal weight and overweight counterparts. Additionally, the infants born to obese mothers have a lower overall neonatal morbidity. These findings may lead to further research into the mechanism behind the increased rate of preterm birth in lower weight women.