PP170. Prenatal vitamin C and E supplementation is associated with a reduction in placental abruption and preterm birth in smokers.

INTRODUCTION: Maternal tobacco use increases the incidence of numerous adverse pregnancy outcomes including miscarriage, small for gestational age infants, spontaneous preterm birth and placental abruption.

OBJECTIVES: We evaluated the relationship between prenatal vitamin C/E supplementation and perinatal outcomes by maternal smoking status.

METHODS: Secondary analysis of a multicenter trial of vitamin C/E starting at 9-16 weeks in low-risk nulliparous women with singletons. We examined the effect of vitamin supplementation by reported smoker or non-smoker at time of randomization. The primary outcomes were preeclampsia (new onset hypertension and proteinuria) and a composite outcome of severe pregnancy associated hypertension (severe hypertension OR mild or severe hypertension with elevated liver enzymes, elevated serum creatinine, thrombocytopenia, eclamptic seizure, fetal growth restriction, medically indicated preterm birth or perinatal death). Perinatal outcomes included preterm birth and abruption. The Breslow-Day test was used to ascertain whether there was an interaction between smoking status and vitamin supplementation.

RESULTS: Of 9969 women, 4993 received vitamins C/E and 4976 received placebo. The prevalence of smoking (15.6% overall; 788 vitamin, 763 placebo) was similar in treatment groups. The analysis of vitamin C/E by smoking status for perinatal outcomes is given (Table 1). The effect of prenatal vitamin C/E on the risk preeclampsia or pregnancy associated hypertension composite outcome did not differ by smoking status. Vitamin C/E was protective for placental abruption and preterm birth among smokers.

CONCLUSION: The effect of vitamin C/E supplementation on preeclampsia/pregnancy associated hypertension did not differ by smoking status. However, vitamin C/E supplementation was associated with a >40% reduction in placental abruption and >30% reduction in preterm birth among smokers warranting further study.

ACKNOWLEDGEMENT: This project supported in part by National Institutes of Health Grant PO1-HD30367.