The combined results of 61 studies conducted in 19 countries suggest that when a woman gives birth by cesarean section, autism in the child is 33% more likely and the odds of attention-deficit/hyperactivity disorder (ADHD) increase by 17%. The statistical analysis, published in JAMA Network Open, does not prove that having a C-section directly causes such problems. Other factors that lead doctors to order a surgical delivery of the baby may underlie the link.