Counseling for fetal macrosomia: an estimated fetal weight of 4,000 g is excessively low

Abstract

Objective: Because of the known complications of fetal macrosomia, our hospital's policy has been to discuss the risks of shoulder dystocia and cesarean section (CS) in mothers with a sonographic estimated fetal weight (SEFW) ≥ 4,000 g at term. The present study was performed to determine the effect of this policy on CS rates and pregnancy outcome.

Study design: We examined the pregnancy outcomes of the macrosomic (≥ 4,000 g) neonates in two cohorts of nondiabetic low risk women at term without preexisting indications for cesarean: (1) SEFW ≥ 4,000 g (correctly suspected macrosomia) and (2) SEFW < 4,000 g (unsuspected macrosomia).

Results: There were 238 neonates in the correctly suspected group and 205 neonates in the unsuspected macrosomia group, respectively. Vaginal delivery was accomplished in 52.1% of the suspected group and 90.7% of the unsuspected group, respectively, p < 0.001. There was no difference in the rates of shoulder dystocia. The odds ratio for CS was 9.0 (95% confidence interval, 5.3-15.4) when macrosomia was correctly suspected.

Conclusion: The policy of discussing the risk of macrosomia with SEFW ≥ 4,000 g to women is not justified. A higher SEFW to trigger counseling for shoulder dystocia and CS, more consistent with American College of Obstetrics and Gynecology (ACOG) guidelines, should be considered.