The influence of body mass index on pregnancy outcomes

To determine antenatal complications, mode of delivery, and birth outcomes for Saint Francis Hospital and Medical Center and Burgdorf Obstetric clinic patient population based on their body mass index (BMI).

This is a retrospective cohort study of 2,270 women who delivered at our institution from 1996 to 2002. Our patient population ranged from ages 23.8 to 26.6 years. The majority of the patients in the study were Black or Hispanic. BMI at delivery was calculated. Maternal data were obtained from our computerized obstetrical database. Exclusion criteria included: nonviable fetus, no recorded maternal height or other incomplete data. For statistical analysis we used a one-way analysis of variance (ANOVA) and a post-hoc Tukey's test, using a computer statistics program (Statmost, Datamost Crop., Salt Lake City, UT), with, P<0.05 considerd significant.

This study revealed that those patients with a higher BMI had greater weight gain during pregnancy. Operative delivery rates were also higher with increasing BMI, as was the infant birth weight. Diabetes and hypertension were directly related to the BMI; the higher the BMI the higher their prevalence. The low number of events recorded did not allow a statistical comparison to determine any increase in shoulder dystocia.

A statistically significant increase in rate of operative delivery, hypertension, diabetes and a trend toward higher birth weight are associated with increased maternal BMI.