[Impact of vaginal delivery after a previous cesarean section on perinatal outcomes].

PURPOSE To analyze the impact of vaginal delivery after a previous cesarean section on perinatal outcomes. METHODS Case-control study with selection of incident cases and consecutive controls. Maternal and perinatal variables were analyzed. We compared secundiparas who had a vaginal delivery after a previous cesarean delivery (VBAC) (n=375) with secundiparas who had a second cesarean section (CS) (n=375). Inclusion criteria were: secundiparas who underwent a cesarean section in the previous pregnancy; singleton and term pregnancy; fetus in vertex presentation, with no congenital malformation; absence of placenta previa or any kind of bleeding in the third quarter of pregnancy. RESULTS The rate of vaginal delivery was 45.6%, and 20 (5.3%) women had forceps deliveries. We found a significant association between VBAC and mothers younger than 19 years (p<0.01), Caucasian ethnicity (p<0.05), mean number of prenatal care visits (p<0.001), time of premature rupture of membranes (p<0.01), labor duration shorter than 12 hours (p<0.04), Apgar score lower than seven at 5th minute (p<0.05), fetal birth trauma (p<0.01), and anoxia (p<0.006). In the group of newborns delivered by cesarean section, we found a higher frequency of transient tachypnea (p<0.014), respiratory disorders (p<0.048), and longer time of stay in the neonatal intensive care unit (p<0.016). There was only one case of uterine rupture in the VBAC group. The rate of neonatal mortality was similar in both groups. CONCLUSIONS Vaginal delivery in secundiparas who had previous cesarean sections was associated with a significant increase in neonatal morbidity. Further studies are needed to develop strategies aimed at improving perinatal results and professional guidelines, so that health care professionals will be able to provide their patients with better counseling regarding the choice of the most appropriate route of delivery.