A fetus estimated to weigh more than 4,000 g (8 lb, 11 oz) or above the 90th percentile weight for gestational age is regarded as macrosomic, and the risks of adverse outcomes for both mother and fetus are increased. The management of macrosomia is highly controversial. Elective planned cesarean delivery for all macrosomic pregnancies is not justified; an estimated 3,600 surgeries would have to be performed on nondiabetic mothers to prevent one permanent neonatal injury. Elective induction of labor has not been shown to reduce the rate of either operative delivery or neonatal morbidity. Sanchez-Ramos and colleagues reviewed the literature to determine the best management strategy for suspected fetal macrosomia.
They searched electronic and print resources for relevant reports produced between 1996 and 2002 to include in a meta-analysis with the principal outcomes of cesarean delivery, shoulder dystocia, and low Apgar score. Of the 29 studies of labor induction for macrosomia identified by the search, 11 met inclusion and quality criteria for the meta-analysis. Two were randomized controlled trials (RCTs), and nine were observational studies. When results were pooled, rates of cesarean delivery were significantly higher in mothers who were induced than in those managed expectantly (16.6 percent compared with 8.4 percent, respectively). This difference persisted after statistical adjustment and regression analysis. When only the two RCTs were considered, the cesarean delivery rate was not increased in the induction group. When data from the nine observational studies were pooled, spontaneous delivery was reported in 82.8 percent of mothers managed expectantly compared with 72.8 percent of those whose labors were induced. The rates of shoulder dystocia (about 6 to 7 percent) and low Apgar scores (1.7 to 1.8 percent) were not significantly affected by labor induction.
The authors conclude that labor induction for macrosomia at term is associated with an increased rate of cesarean delivery without improving outcomes. Although the current evidence is incomplete, a policy of expectant management appears to be reasonable.