Clinical Significance of Pregnancies with Macrosomia (Birth Weight ≥ 4,000 g) Compared with Deliveries with Neonatal Birth Weight of 3,500-3,999 g.

Introduction: We examined the clinical characteristics and perinatal outcomes of pregnancy with macrosomia (birth weight ≥ 4,000 g) compared with delivery with neonatal birth weight of 3,500-3,999 g.

Methods: This study analyzed data obtained from singleton pregnant women who delivered at ≥22 weeks of gestation from January 2002 to December 2010.

Results: During the study period, there were 12,497 singleton deliveries, of which 136 (1.1%) had macrosomia (average: 4,181 g, range: 4,000-4,726 g; macrosomia group) and 1,139 (9.1%) had neonatal birth weight of 3,500-3,999 g (average: 3,670 g; control group). Compared with the control group, the macrosomia group had advanced maternal age and births after 41 weeks of gestation. In addition, elective cesarean delivery was more common in the macrosomia group (P < 0.01). Furthermore, the rate of shoulder dystocia was higher in this group in cases of vaginal delivery (P < 0.01). A high rate of neonatal asphyxia was also observed in the macrosomia group (P < 0.01), although there were no significant differences in the rate of low umbilical artery pH or the incidence of neonatal hypoglycemia between the groups. Multivariate analysis revealed that the significant complications in the macrosomia group compared with the control group were shoulder dystocia (P = 0.01) and neonatal asphyxia (P = 0.03).

Conclusions: The results of this study indicate that particular attention should be paid to the possibility of shoulder dystocia during delivery of macrosomia.