Effect of pre-pregnancy maternal body mass index on pregnancy outcomes in nulliparous women in the Islamic Republic of Iran

This study was conducted to evaluate the effect of pre-pregnancy BMI on pregnancy outcomes. BMI was calculated measured in 360 nulliparous women. According to BMI, pregnant women were placed into three groups: group I (lean group BMI <= 19.8), group II (normal weight group BMI = 19.9-24.9), and group III (obese group BMI >= 25). Data were analyzed using SPSS 16. The mean duration of the first and the second stage of labour were significantly different between three groups (P < 0.001). Cesarean section ratio in group I was lower than group II (OR = 0.15; P = 0.013). Instrumental delivery in group III was more than group II (OR=4.6; P = 0.002). Risk of nonreactive non-stress test (NST) was significantly different between groups II and III (OR = 5.7; P = 0.009). Induction ratio in group I was lower than group II (OR=0.43; P = 0.002). Deviation of BMI from the normal level is associated with adverse outcomes of pregnancy and delivery.