Babies born by Caesarean section have a 50% increased risk of developing asthma compared to babies born naturally, according to a study out of Norway. In addition, babies born by an emergency Caesarean section had an even higher risk of developing asthma.
Researchers studied the births of 1.7 million babies registered at the Medical Birth Registry at the Norwegian Institute of Public Health. All of the subjects were born between 1967 and 1998.
“We found a moderately strong association between birth by Caesarean section and asthma in childhood,” says Mette Christophersen Tollånes, MD, of the Norwegian Institute of Public Health.
Two main theories lie behind this increased risk. First, babies born by Caesarean section are not exposed to their mothers’ bacteria during birth, which is detrimental for development of the immune system. The second theory is that babies born by Caesarean section have more breathing problems after birth because they are less exposed to stress hormones and compression of the chest, since these mechanisms contribute to emptying the lungs of amniotic fluid, which could negatively affect lung function long-term.
The full study was published in the Journal of Pediatrics.