Maternal anthropometric factors and risk of primary cesarean delivery

OBJECTIVES: This study examined absolute and proportional gestational weight gain and prepregnancy body mass index as predictors of primary cesarean delivery. METHODS: Data were derived from a prospective study of pregnancy outcome risk factors in 2301 women in greater New Haven, Conn, who had singleton deliveries by primary cesarean (n = 312) or vaginal delivery (n = 1989) and for whom height, prepregnancy weight, and weight gain were available. Women were divided into 4 body mass index groups (underweight, low average, high average, and obese) and further subdivided into 8 groups according to median proportional or absolute weight gain. RESULTS: Risk of cesarean delivery increased with increasing body mass index and gestational weight gain greater than the median for one's body mass index. Proportional weight gain was more predictive of cesarean delivery than absolute weight gain. Underweight women gaining more than 27.8% of their prepregnancy weight had a 2-fold adjusted relative risk of cesarean delivery. CONCLUSIONS: Proportional weight gain is an important predictor of cesarean delivery for underweight women; high body mass index is also predictive of increased risk.