Previous research has raised the possibility of a causal link between Cesarean delivery and autism spectrum disorders, both of which are on the rise.
But a new two-part study should go a long way in reassuring parents whose babies are born via C-section that their children are not at any greater risk of developing the disorder because of how they were delivered.
Researchers with the Irish Center for Fetal and Neonatal Translational Research analyzed data on deliveries and subsequent autism diagnoses among nearly 2.7 million children born in Sweden in the past three decades. Children born via elective C-section were roughly 20 percent more likely to be diagnosed with autism, which was in line with previous estimates.
However, when the researchers further analyzed the mode of delivery among more than 13,400 pairs of siblings in which one child was diagnosed with autism and the other was not, the association did not hold up. They concluded that any link was likely due to unknown genetic or environmental factors and not because of how the children were delivered.
"Based on our data, there is no evidence that birth by Caesarean section causes ASD," study co-author Ali Khashan of the Irish Center for Fetal and Neonatal Translational Research in Cork, Ireland, told The Huffington Post in an e-mail. His team's findings were published in JAMA Psychiatry on Wednesday.
Previously, researchers have surmised that certain factors associated with C-sections, such as changes in the microbiota or differences in the types of anesthesia used, might potentially influence subsequent autism risk.
But Khashan argued that it is now safe to assert that those hypothetical mechanisms "play no role in the association between Caesarean section and ASD." He added that the new study had the largest sample size of any looking at the potential link to date -- however, he did caution that it was based in only one country.
In many circumstances, C-sections are essential to protect the lives and health of mothers and babies, although some countries -- including the United States -- have rates at least double the World Health Organization's recommendation of 15 percent. Little is known about the potential longterm consequences associated with the surgery, but a growing body of research has begun to tackle that question. An investigation published earlier this month, for example, found a link between C-sections and chronic health problems including asthma, diabetes and obesity. It did not, however, establish cause and effect.
"Caesarean section rates are increasing worldwide and more research is needed to help us better understand the benefits and risks," Khashan said. "This would help women and clinicians make an informed decision on the most suitable mode of delivery [for them]."