Is prenatal identification of fetal macrosomia useful?

Objectives: To determine whether prenatal identification of macrosomia (≥4000g) reduces neonatal complications and maternal perineal lesions during delivery.

Study Design: This historical cohort study (n=14,684 from the National perinatal database of the Audipog Association, France) included women with cephalic singleton term pregnancies. Among the babies born with macrosomia, we compared those who had been identified as such in utero (n=1211) with those who were not (n=13,473). The principal outcome was a composite variable defined as resuscitation in the delivery room, death in the delivery room or the immediate postpartum period, or transfer to a neonatal intensive care unit (NICU). The secondary outcome measures were neonatal trauma, 5-min Apgar score (≤4 and <7), and maternal perineal lesions. Results are expressed as crude relative risks and adjusted odds ratios.

Results: The mean birthweight in the cohort was 4229g±219. The adjusted OR for the principal outcome defined above was 1.15 (95% CI: 0.89-1.50) in the group identified prenatally as macrosomic compared with the others (10.8% vs. 8.5%). The risk of neonatal trauma was higher in prenatally identified babies (adjusted OR: 1.80; 95% CI: 1.34-2.42). The 5-min Apgar score and the perineal lesion rate did not differ significantly between the groups. The a posteriori study power according to our results with α=0.05 was 84% (one-sided test).

Conclusions: Among babies born with macrosomia, in utero identification did not improve neonatal or maternal outcomes.