Does a lean prepregnancy body mass index influence outcome in pregnancies complicated by mild preeclampsia remote from term?

Objectives. To determine the influence of a lean prepregnancy body mass index (BMI) on pregnancy outcome in women with mild preeclampsia. Study Design. A matched cohort design was used. A total of 99 pregnant women with mild preeclampsia and a nonobese prepregnancy BMI (22-28 kg/m(2)) were matched 1 : 1 for gestational age at diagnosis, race, and parity to 99 women with mild preeclampsia, but a lean prepregnancy BMI (less than or equal to 20 kg/m(2)) . All patients were enrolled in an outpatient management program between 24 and 36 weeks' gestation for a minimum of 2 days, had singleton pregnancies, and exhibited proteinuria of of greater than or equal to 1 + at the start of the program. Outpatient monitoring included automated blood pressure measurements and daily assessment of weight, proteinuria, and fetal movement. Results. The mean gestational age at enrollment was 33.4 +/- 2.8 weeks for both groups. By matching, 65% of patients in each group were nulliparous and 79% of patients in each group were of the white race, There were no patients in either group with a history of preterm delivery. The mean gestational age at delivery (36.8 +/- 2.3 versus 36.3 +/- 2.3 weeks, p = 0.047) was greater in the lean prepregnancy BMI group with a lower cesarean section rate (32% versus 52%, p = 0.006) but similar mean birth weights (2728 +/- 698 versus 2679 +/- 802 g, p = 0.635). There were two perinatal deaths in the lean prepregnancy BMI group and one in the nonobese prepregnancy BMI group (p = 1.0). Conclusion. In patients with mild preeclampsia remote from term, a lean prepregnancy BMI was associated with a later gestational age at delivery and a reduced incidence of cesarean delivery. Neonatal outcomes, however, did not differ significantly between the groups.