Elective induction versus spontaneous labor after sonographic diagnosis of fetal macrosomia

To test the hypothesis that elective induction of labor, compared to spontaneous labor, reduces the cesarean rate in women with a sonographic diagnosis of fetal macrosomia.

Sonography results over a period of 27 months were used to select 262 consecutive patients who met the following inclusion criteria: singleton pregnancy at term, estimated fetal weight (EFW) at the 90th percentile or greater, and delivery at our institution. The subjects were divided into four groups based on obstetric management: spontaneous labor (N = 115), elective induction of labor with macrosomia as the sole indication (N = 44), induction of labor for other maternal or fetal indications (N = 48), and elective cesarean delivery (N = 55). The analysis focused on the first two groups. These were compared regarding cesarean rate, indications for cesarean, and shoulder dystocia rate. Multiple logistic regression was used to control for potential confounders.

With elective induction, the cesarean rate was 57%, significantly higher than the 31% rate with spontaneous labor (P < .01). The induced group also had a significantly higher EFW and birth weight. When logistic regression was used to control for birth weight, parity, and care provider, elective induction was still associated with a higher risk of cesarean delivery than was spontaneous labor (adjusted odds ratio 2.7, 95% confidence interval 1.2-5.9; P < .02). Shoulder dystocia occurred in one of 19 vaginal deliveries with elective induction (5.3%) and in two of 79 with spontaneous labor (2.5%).

Because elective induction of labor increased the cesarean rate and did not prevent shoulder dystocia, we conclude that mothers with macrosomic fetuses can safely be managed expectantly unless there is a medical indication for induction.