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Artificially stimulating labor is associated with a slightly higher risk of autism, but researchers caution that the link may be complicated.

In a study published in the journal JAMA Pediatrics, women who needed to jump-start their labor or artificially speed up delivery were up to 23% more likely to have children diagnosed with autism than those who didn’t avail themselves of these methods.

The scientists stress, however, that it’s not clear whether the delivery method was responsible for the higher rate of the developmental disorder, or whether babies with autism don’t send the proper signals for a timely and speedy birth. But given the relationship, the researchers, based at Duke University and the University of Michigan, say the connection between delivery methods and autism is worth exploring, especially since the rates of both induction and augmentation are rising around the country.

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The scientists came to their conclusion after reviewing birth records for 625,000 babies in North Carolina over an eight-year period that were matched with the children’s corresponding public school records, which contained diagnoses of autism. For children who were born after induced labor, the risk of autism was 13% higher compared with that of children born to mothers who were not induced; speeding up labor was associated with a 16% higher risk of autism, while both induction and augmentation were linked to a 23% greater risk of autism in children. The researchers estimate that 2 in every 1,000 autism cases might be eliminated without labor induction or augmentation. That risk is similar to that of other autism risk factors, such as a mother’s age or being born early.

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“I think we’re at a point in autism research where we are really looking to uncover any possible risk factor. What this tells us is that the period around pregnancy is a very important stage in the development of a child. It seems to be a critical period for exposure to potential risk factors that might increase risk for autism. We are seeing that again in this study,” says Michael Rosanoff, associate director of Autism Speaks, who was not unaffiliated with the study. “It’s not a huge risk, but the fact that so many women may be exposed to this risk factor is what’s important and what warrants additional research into the actual mechanisms behind this association.”

The findings contribute to the growing knowledge of risk factors involved in the disorder, but the researchers recognize that induction, which is usually accomplished by giving the mom the labor hormone oxytocin, either applied directly to the cervix or in an intravenous drip, can reduce the risk of stillbirth. Speeding up labor can also lower infections in both mom and baby during delivery.

So it’s important for more studies to tease apart what is driving the association. A developing baby with autism, for example, may be affecting the pregnancy, in which case the induction is not an indicator of autism but rather a result of it. “Additional studies are needed to differentiate among potential explanations of the association, such as underlying pregnancy conditions requiring the eventual need to induce [or] augment, the events of labor and delivery associated with induction [or] augmentation, and the specific treatments and dosing used to induce [or] augment labor,” the study’s senior author Marie Lynn Miranda, dean of the University of Michigan’s School of Natural Resources and Environment, said in a statement.

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“It’s extremely important to note that there is no causal association here. In other words, induction or augmentation of labor does not cause autism, but it may increase risk,” says Rosanoff. “For parents who are concerned, the best thing to do right now is to become educated on healthy pregnancy, typical development, and early warning signs of autism. Right now the picture isn’t clear enough from this study or what we know of risk factors for autism for doctors to change their recommendations or for parents to change their behaviors.”