Aim: We aimed to illustrate the relationship between maternal obesity during pregnancy and maternal and fetal outcomes. We examined the influence of maternal BMI at the beginning of pregnancy on risks of pregnancy and birth, and on the somatic classification of the neonates.
Material and methods: In our retrospective cohort study we included 499,267 singleton pregnancies taken from the German perinatal statistics of 1998-2000. 51,506 obese pregnant women (BMI >or= 30) were compared to 320,148 pregnant women of normal weight (BMI 18.50-24.99). We divided obesity into 3 BMI-categories: BMI = 30.00-34.99, BMI = 35.00-39.99, and BMI >or= 40.00. We defined small-for-gestational-age (SGA), appropriate-for-gestational-age (AGA), and large-for-gestational-age (LGA) status by birth weight percentiles.
Results: 10.3 % of all pregnant women had a BMI >or= 30.00 and 0.8 % had a BMI >or= 40.00. The frequency of hypertension increased with the extent of obesity: 7.1 % (BMI = 30.00-34.99), 12.5 % (BMI = 35.00-39.99) and 18.3 % (BMI >or= 40.00) compared to 1.2 % (BMI 18.50-24.99). Cephalopelvic disproportion was found in 6.8 % (BMI >or= 40.00) compared to 2.8 % (BMI 18.50-24.99). Fetal macrosomia occurred in 24.8 % (BMI >or= 40.00) compared to 7.9 % in the control group. Rates of pre-eclampsia, gestational diabetes, and fetal structural anomalies also increased with maternal BMI. Women with different BMIs differed in parity but not in age.
Conclusions: Obesity during pregnancy is associated with a range of maternal and fetal adverse outcomes. Pregnancy in obese women therefore calls for close monitoring and careful planning of delivery. Pre-conceptional weight reduction should be considered.