Objective: Our objective was to investigate the relationship between prepregnancy and obstetric body mass index (BMI) as well as fetal complications in a large, unselected cohort of Danish women with single cephalic pregnancies.
Methods: A cohort of 8,092 women from the Copenhagen First Trimester Study with a registered prepregnancy BMI and a single cephalic term delivery were stratified into 3 BMI groups: normal weight (BMI < 25 kg/m(2)), overweight (BMI 25-29.9 kg/m(2)), and obese (BMI >/= 30 kg/m(2)). The effects of BMI and parity on the outcome were analyzed using multivariate logistic regression analyses.
Results: Overweight women had an odds ratio (OR) of 3.4 for diabetes, 1.9 for hypertension, 1.7 for preeclampsia, and 1.5 for cesarean delivery. The corresponding figures for obese women were 15.3, 4.8, 2.7, and 1.7, respectively. No relationship was found between BMI and vacuum extraction. Obese women had an increased risk of delivering macrosomic but also low birth weight children. No differences existed among the 3 weight groups with regard to neonatal morbidity estimated by Apgar score, umbilical cord pH, or admittance to a neonatal intensive care unit. Nulliparous women had an increased incidence of preeclampsia (OR 2.8), hypertension (OR 1.9), emergency cesarean delivery (OR 3.4), vacuum extraction (OR 5.6), and perineal rupture (OR 1.7) but a lower frequency of elective cesarean delivery (OR 0.25).
Conclusion: The rate of complications during pregnancy and delivery increases with an increasing prepregnancy BMI in women with single cephalic term pregnancies, particularly in nulliparous women.