Pregnant women given drugs to speed up labour had a 35% higher risk of autism in boys compared to non-induced labour, found the study of 625,000 births that included 170,000 births induced or augmented over eight years.
Smaller studies have hinted at the connection but the latest research published this week in JAMA Pediatrics is the largest, most comprehensive to date, propping up suggestions that autism is the result of a combination of genetic and environmental factors.
No significantly heightened risk was seen in girls born after induced labour but those whose birth were accelerated had an 18% higher risk of autism compared to those who were neither induced or augmented, reported the researchers at the University of Michigan School of Natural Resources.
Labour-inducing drugs may drive up the risk, according to the study, but the authors stopped short of implicating induced labour as the cause of the disorder.
On the other hand, medical conditions that prompt doctors to recommend inducing and accelerating labour such as diabetes and fetal complications may also play a role.
The higher risk was similar to that of older mothers or giving birth before 34 weeks.
“This study provides preliminary evidence of an association between autism and labour induction/augmentation, especially among male children,” said co-author Marie Lynn Miranda and dean of the University’s School of Natural Resources and Environment.
But they warned that doctors should not avoid inducing labour to mitigate the potential autism risk.
As first appeared in Psychiatry Update, 14 August 2013. Source: JAMA Pediatrics, 2013