THE PRETERM PREDICTION STUDY - ASSOCIATION OF CESAREAN DELIVERY WITH INCREASES IN MATERNAL WEIGHT AND BODY-MASS INDEX

OBJECTIVE: Our purpose was to evaluate whether maternal weight and bod y mass index measured either before or during pregnancy are associated with an increased risk of cesarean delivery. STUDY DESIGN: Maternal w eight and height were prospectively collected on 2929 women in the Nat ional Institutes of Health Maternal-Fetal Medicine Units Network Prete rm Prediction Study. Prepregnancy and 27- to 31-week maternal weight a nd height were used to calculate the body mass index, and its contribu tion to the risk of cesarean delivery was determined. Women with prena tally diagnosed congenital anomalies (n = 89) and pregestational diabe tes (n = 31) were excluded from analysis. RESULTS: Univariate analysis of risk factors for cesarean delivery in the 2809 eligible women reve aled a decreased risk of cesarean delivery with maternal age <18 years and multiparity; increased risk of cesarean delivery was noted with m aternal age >35 years and a male fetus. Increases in either prepregnan cy or 27- to 31-week maternal weight (5-pound units) or body mass inde x (1.0 kg/m(2) units) were significantly associated with an increased odds of cesarean delivery (p = 0.0001). Each unit increase in prepregn ancy or 27- to 31-week body mass index resulted in a parallel increase in the odds of cesarean delivery of 7.0% and 7.8%, respectively. Mult ivariable stepwise logistic regression analysis confirmed the associat ion of male fetus, age, nulliparity, and body mass index as significan t variables contributing to cesarean delivery risk. CONCLUSIONS: The r isk of cesarean delivery is associated with incremental changes in mat ernal weight and body mass index before and during pregnancy after adj ustment for potential confounding factors. Prepregnancy counseling abo ut optimizing maternal weight and monitoring weight gain during pregna ncy to decrease the risk of cesarean delivery are supported by this st udy.