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Study Links Induced Labor and Autism Risk

Christopher Astacio reads with his daughter Cristina, 2, who was diagnosed with a mild form of autism. A new study links induced labor with increased risk of autism.
Women who undergo induced or augmented labor during childbirth may increase the risk their baby will be autistic, according to a new study. The risk may even be higher if the baby is a male.

“Inducing or augmenting labor has been previously suggested as a contributing factor to autism development,” said the study’s lead author, Simon G. Gregory, associate professor of medicine and medical genetics at Duke University. “However, these studies produced conflicting results and consisted of a relatively small number of subjects. Our study is by far the largest one of its kind to look at the association between autism and induction or augmentation.”

Researchers at the University of Michigan and Duke University, looked at records of all births in North Carolina over an eight-year period and matched 625,042 births with corresponding public school records, which indicated whether children were diagnosed with autism.

Approximately 1.3 percent of male children and 0.4 percent of female children had autism diagnoses. In both male and female children, the percentage of mothers who had induced or augmented labor was higher among children with autism compared with those who did not have autism.

Autism is a developmental disability that can cause social, communication and behavioral difficulties. It affects approximately one in 88 children in the United States.

Gregory said the increased risk associated with induced labor is similar to other known autism risk factors, including a mother being older or a baby being born before 34 weeks of gestation. Additional analysis suggests that not inducing labor might eliminate two in every 1,000 autism cases among male children born to mothers who underwent induced labor.

The latest government data suggest one in five U.S. women have labor induced — twice as many as in 1990. Induced labor — stimulating contractions before the onset of spontaneous labor -- has been shown to prevent complications, including stillbirth.

“The findings of this study must be balanced with the fact that there are clear benefits associated with induction and augmentation of labor,” said study co-author Chad A. Grotegut, assistant professor of obstetrics/gynecology at Duke University Medicine. “Labor induction, especially for women with post-date pregnancies or medical conditions such as diabetes and high blood pressure, has remarkably decreased the chance of stillbirth.”

Researchers caution that the study “does not prove cause and effect,” but that the results call for more study of the relationship between induced labor and autism.

For example, the researchers noted that some information that could have benefitted their analyses was not available, including detailed data on the children’s autism diagnoses. No information was available on the severity of autism, nor were records available for children diagnosed with autism who did not attend a public school.

The researchers also did not have access to the full maternal or child medical records, which would provide more detailed information on the pregnancy and events of labor and delivery.

“The scientific community has long looked for environmental contributors to the rising rates of autism in the United States,” said Marie Lynn Miranda, senior author of the paper and a professor in both Environmental Informatics and Pediatrics at the University of Michigan. “This study provides preliminary evidence of an association between autism and labor induction/augmentation, especially among male children.”

The findings were published this week in JAMA Pediatrics.