A new study based on data from 1.7 million births has shown that babies born by Caesarean section have a 50% increased risk of developing asthma compared to babies born naturally. The study was performed at the Medical Birth Registry at the Norwegian Institute of Public Health. The goal of the study was to investigate the possible link between being born by Caesarean section and later development of asthma.
Emergency Caesarean sections increase the risk even further. Compared to children born in the natural way (i.e. spontaneously and vaginally), children born by Caesarean section had an approximately 50% increased risk of developing asthma. Children born vaginally, but with assistance from vacuum or forceps, had a 20% increased risk of asthma. For children born between 1988 and 1998, planned Caesarean section was associated with an approximately 40% increased risk of asthma while emergency Caesarean section was associated with a 60% increased risk.
The first question I asked after reading the research summary was why do Caesarean sections give an increased risk of asthma? Mette Christophersen Tollånes, the doctor who works for both the Norwegian Institute of Public Health, is the first author of the article ”Cesarean Section and Risk of Severe Childhood Asthma: A Population-Based Cohort Study” which is published in the Journal of Pediatrics.
"Babies who are born by Caesarean section are not exposed to their mothers’ bacteria during birth, which is detrimental for development of the immune system. The other 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. Maybe this can negatively affect lung function in the long term," says Tollånes.