Cesarean section in absence of labour and risk of respiratory complications in newborns: a case-control study.

Aim: To establish if labor and gestational age have an additive effect on the likelihood of newborn respiratory complications. Methods: Case-control study on singleton pregnancies, delivered between 34 and 41 weeks. Cases were collected among newborns discharged with diagnoses of respiratory complications, as codified by ICD 9 1997. Subsequently, pneumonias, meconium aspiration syndromes, and pulmonary hemorrhage were excluded. Controls were all other newborns without respiratory complications. Multivariate analyses were performed hypothesizing and not hypothesizing a relationship between gestational age, labor and newborn adverse respiratory outcomes. Results: Twenty thousand three hundred and ninety-seven living babies born at term or near-term between January 2006 and December 2010 were assessed. 16,084 infants were included in the analyses. 304 experienced a respiratory complication (cases group). Delivering by cesarean not in labor increases the odds ratio of adverse respiratory outcome by about 2, independently from other variables, among which is gestational age. The same increase of odds ratio of 2 is constantly observed at each week of gestation, from 35 to 39 gestational weeks. Conclusions: Cesarean not in labor adds a constant risk of newborn respiratory complications at any gestational age near-term and early-term. The more the planned cesarean is delayed, the better is newborn respiratory outcome.