Influence of maternal anthropometric status and birth weight on the risk of cesarean delivery

To determine whether greater weight gain during pregnancy is associated with an increased risk of cesarean delivery, and, if so, whether this effect is explained by the positive influence of weight gain on birth weight and if there is a threshold of pregnancy weight gain above which the risk of cesarean delivery is increased differentially.

We analyzed live births at Johns Hopkins Hospital for the period 1987-1989. A multiple logistic regression model was used to evaluate the risk of cesarean delivery, recorded in the hospital's perinatal data base.

The study sample contained 4346 patients, 1086 of whom delivered by cesarean. Associated independently with an increased risk of cesarean delivery were the following: 1) greater weight gain during pregnancy, 2) older maternal age, 3) greater maternal prepregnant body mass index, 4) maternal height of 1.57 m or less, 5) the diagnosis of preeclampsia during current pregnancy, and 6) carrying a fetus weighing more than 3591 g at birth. An additional risk factor for cesarean delivery was a fetus less than 2847 g at birth, with the risk more marked the lower the gestational age. Maternal height of 1.73 m or more and a history of at least one previous viable pregnancy were associated independently with a decreased risk of cesarean delivery.

The risk of cesarean delivery increases linearly with pregnancy weight gain, independent of birth weight. No specific threshold of weight gain can be determined above which the cesarean risk climbs more rapidly.