The frequency of caesarean section and neonatal outcomes depending on management strategy for large-for-gestational-age pregnancy

Fetal macrosomia is a risk factor for adverse obstetric outcomes, such as operative vaginal delivery, cesarean section and shoulder dystocia. With fetal macrosomia, the effectiveness of reducing the frequency of operative delivery is still a matter of debate. More promising is to study a possibility of early-term delivery in women with large-for gestational-age (LGA) fetuses, who have not yet reached the criteria for defining macrosomia.

Objective: To evaluate the frequency of operative delivery in pregnant women with LGA fetuses, depending on management strategy (pre-induction/ induction of labor or expectant management) and gestational age.

Materials and methods: A retrospective cohort study included 478 healthy primiparous women with delivery of large-for-gestational age fetuses according to ultrasound data. The women were divided into two groups. The comparison group was expectant management (n=195) and the main group was induction of labor (n=283). Both groups were divided into three subgroups depending on gestational age: subgroup 1 included women who were 38 weeks pregnant, subgroup 2 – 39 weeks, subgroup 3 – 40 weeks.

Results: The frequency of cesarean section in the group of women with spontaneous onset of labor at 38 and 39 weeks was 33.3% and 20.5% versus 22.2% and 17.1% in the induction group (p>0.05). At the same time, the frequency of cesarean section at 40 weeks was significantly lower in the expectant management group, 21.8% versus 36.9%, p=0.02. There were no differences between the rates of vaginal delivery, fetal shoulder dystocia, and perinatal outcomes. However, in the expectant management group at 39 weeks, there were significantly more newborns with Apgar score of 7 or less, 12.8% versus 4.04% in the induction group, p=0.04.

Conclusion: In most cases, the formation of macrosomia was between 39–40 weeks, and induction of labor as a method for preventing complications associated with macrosomia was ineffective. It is apparent that, the optimal gestational age for delivery was 39 weeks for ultrasound-estimated fetal weight equal to the 90th percentile, 38 weeks for the 95th percentile, and 37–38 weeks for the 97th percentile.