Optimal gestational age of delivery to decrease neonatal morbidity in preterm pregnancies in Korea

Preterm birth is the most common cause of neonatal morbidity and mortality. Neonatal morbidity and mortality are known to decrease significantly after 34 weeks in preterm births following preterm labor, and after 32 weeks in preterm births following preterm rupture of the membranes. However, these outcomes may not apply to Korean preterm neonates. This study analyzed the morbidity of preterm neonates based on gestational age to determine the optimal gestational age of delivery following preterm labor.

We retrospectively analyzed the medical records of preterm neonates and their mothers who delivered at Seoul St. Mary's Hospital between January 1995 and December 2007.

Among 1234 preterm neonates, 1008 were singletons and 226 were multiple births. In both singleton and multifetal pregnancies, the maternal characteristics did not differ based on gestational age. The 1- and 5-min Apgar scores were significantly lower than at 35 weeks in singleton births, and at 33 weeks in multiple births. Major complications, such as intraventricular hemorrhage and the use of a respirator, decreased significantly after 35 weeks in singleton births, and after 33 weeks in multiple births.

The optimal gestational age for decreasing the morbidity of major complications in preterm neonates was 1 week later than the American College of Obstetricians and Gynecologists recommendations. For Korean mothers with preterm labor, delivery needs to be delayed until 35 weeks in singletons, 33 weeks in twins, and 32 weeks in singletons with preterm rupture of the membranes.