NEW YORK (Reuters Health) - Full-term neonates delivered through elective repeat cesarean have higher rates of respiratory morbidity, hypoglycemia, and admission to a neonatal intensive care unit (NICU) than infants delivered by vaginal birth after a previous cesarean, investigators in Denver report in the June issue of Obstetrics & Gynecology.

“Controversy remains on whether a trial of labor or an elective repeat cesarean delivery is preferable for a woman with a history of cesarean delivery,” Dr. Beena D. Kamath at the University of Colorado Denver School of Medicine and her colleagues note. Based on risk of uterine rupture and perinatal asphyxia, obstetricians often favor elective repeat cesarean.

To compare the outcomes of elective cesarean versus vaginal birth after cesarean delivery, the team studied 672 women with one prior cesarean and a singleton pregnancy without congenital anomalies, who delivered at term between 2005 and 2008.

Subjects were categorized into four groups: elective repeat cesarean without labor (n = 239); elective cesarean after onset of labor (n = 104); successful vaginal birth after cesarean (n = 244); or failed vaginal birth after cesarean requiring emergent cesarean delivery (n = 85).

Overall, neonates born by cesarean had higher NICU admission rates compared with those born by vaginal birth after cesarean (9.3% vs 4.9%, p = 0.025). Intended repeat cesarean was associated with a higher incidence of NICU admission for hypoglycemia and higher rates of oxygen supplementation and ventilatory support.

The authors theorize that “the catecholamine surge that occurs during labor likely plays an important role in both clearance of fetal lung fluid and glycemic control after birth.”

More specifically, however, women who failed vaginal birth and required cesarean delivery were most likely to exhibit fetal distress requiring resuscitation, whereas a successful vaginal birth after previous cesarean had the fewest admissions to the NICU, shortest hospital stay, and the lowest incidence of ongoing respiratory support.

These findings, say Dr. Kamath and her colleagues, argue for “greater selectivity in performing a cesarean delivery in the first place, and certainly a greater need for counseling before a primary elective cesarean delivery.”

Obstet Gynecol 2009;113:1231-1238.