[Cesarean delivery at term in low risk pregnancies: effects on neonatal morbidity]

The rate of cesarean delivery (CD) has significantly increased over the last years, even in low risk pregnancies. Our objective was to compare the neonatal morbidity rate in low risk term infants delivered by vaginal or CD.

Prospective observational and analytical cohort study. Main outcome measures. Incidence of any neonatal morbidity and respiratory morbidity. Population and methods. Infants < or = 37 weeks born at the Hospital Italiano de Buenos Aires between December 2004 and July 2006 were eligible. Exclusion criteria included: any maternal related disorder, acute or chronic fetal distress, breech presentation in primiparous women, multiple pregnancies, intrauterine growth restriction and newborns with major malformations.

A total of 2021 infants were included, 1120 born vaginally and 901 by CD. Main indications for CD were failure to progress labor (46%) and previous CD (37%). Only 3% of CD was performed by maternal request. Any neonatal morbidity rate was 9% in infants born by CD and 6.6% in infants born vaginally (RR 1.36; 95%CI 1.01-1.8). Respiratory morbidity rate was 5.3% in infants born by CD and 3.1% in those born vaginally (RR 1.7; 95%CI 1.1-2.6). When stratified by gestational age, respiratory morbidity was higher only for infants < or =38 weeks (7.4% in CD vs. 2.1% in vaginal delivery; RR 3.5; 95%CI 1.5-8.1). Also, respiratory morbidity was higher in infants born < or =38 weeks by CD without labor vs. those with labor 10.5% and 3.9%, respectively (RR 1.35; 95%CI: 1.07-1.70). In a logistic regression analysis, CD and male sex were independently associated with higher respiratory morbidity. There were not significant differences in other morbidities. NICU admission was higher in infants born by CD (9.5% vs. 6.1%; RR 1.5; 95% CI: 1.1-2.1). Sixty-eight percent of the mothers from the CD group refereed having moderate to severe pain in the puerperium vs. 36% in the vaginal group (RR 1.9; 95% CI: 1.7-2.1). Exclusive breastfeeding at discharge was significantly lower in infants born by CD (90% vs. 96%; RR 0.94 95%CI 0.92-0.96).

Low risk CD at term was associated with a higher neonatal morbidity, NICU admission and maternal pain in the puerperium. It also reduces exclusive breastfeeding rate at discharge.