A study has revealed that babies delivered by elective caesarean section around term face up to four times the risk of breathing problems as compared with babies delivered vaginally or by emergency caesarean section.
The study, conducted by researchers at the Aarhus University Hospital in Denmark, stated that the exact reasons for this are unknown, but one explanation is that hormonal and physiological changes associated with labour are necessary for lungs to mature and that these changes may not be present in infants delivered by elective caesarean section.
Gestational age at the time of elective caesarean section may also be important.
In the study, the scientists investigated the association between elective caesarean sections and newborn respiratory problems. They also analysed the importance of timing of elective caesarean sections, reports British Medical Journal.
In the main analysis over 34,000 live born singleton babies without birth defects and with gestational ages of 37 to 41 weeks were included.
Deliveries were categorised into two groups: elective caesarean section and intended vaginal delivery i.e. all vaginal deliveries and emergency caesarean sections.
Factors such as maternal smoking and alcohol intake during pregnancy, maternal body mass index, maternal age and education, were also taken into account because they could affect the results.
2,687 infants were delivered by elective caesarean section. Compared with infants intended for vaginal delivery, infants delivered by elective caesarean section were found to have an increased risk of general respiratory problems.
A nearly fourfold increased risk was found at 37 weeks gestation, a threefold increase in risk at 38 weeks gestation, and a doubling of risk in infants delivered at 39 weeks gestation.
The analyses after restriction to low risk pregnancies revealed slightly smaller risk estimates at 37 weeks gestation but essentially unchanged estimates at 38 and 39 weeks gestation for serious respiratory problems, whereas the estimates remained unchanged at all gestational ages for general respiratory problems.
The researchers said that babies delivered by elective caesarean section at 37 to 39 weeks of gestation carried a two to fourfold increased risk of respiratory morbidity compared with babies delivered by intended vaginal delivery.
They suggested that a significant reduction in neonatal respiratory morbidity might be obtained if elective caesarean section is postponed until 39 completed weeks of gestation.
The study is published in the British Medical Journal.