Researchers from the University of Edinburgh examined data from 79 large scientific studies, analyzing 29 million births.
The findings, published recently in the PLOS One journal, revealed that children under five delivered via C-section had a 59 percent greater chance of being obese. This group was also 21 percent more likely to have asthma by the time they reached 12 years of age.
Scientists believe that C-sections may affect the development of gut bacteria and the immune system. They speculate that the increased risk result from C-section babies not being exposed to bacteria they would have had they journeyed through the birth canal. Without exposure to such bacteria, their metabolisms, ability to store fat and ability to protect themselves against allergies that cause wheezing are affected.
The study also revealed that women who had previously had a C-section were more likely to have complications during future pregnancies. For such women, stillbirth rates increased by 17 percent while miscarriage increased by 27 percent. However, they had a 56 percent lower chance of urinary incontinence.
The University of Edinburgh's Dr. Sarah Stock said, "Although we cannot conclude that caesarean delivery causes certain outcomes, pregnant women and clinicians should be aware that caesarean delivery is associated with long-term risks for the baby and for subsequent pregnancies," suggesting that pregnant women should carefully consider the risks of a C-section delivery.
Dr. Rachel Tribe at King's College London agreed: "This systematic review and meta-analysis is a very useful contribution to our understanding of the ‘pros and cons' of elective caesarean section."
Andrew Shennan, professor of obstetrics at King's College London, also commented on the study. "The outcomes have a plausible mechanism which suggests causation in spite of the observational nature of most of the studies informing this review," he said.
"Risks to future pregnancies were potentially serious, including an increase in miscarriages and stillbirths, so mothers may accept small risks to herself to reduce these risks to her potential future babies by avoiding unnecessary caesarean sections," he added.