Diabetes that develops early in pregnancy increases the risk of autism by 40 percent, according to a large new study of more than 320,000 children and their mothers.
The increased risk may stem from the effects of uncontrolled high blood sugar during a critical window of early brain development, the investigators suggest. Their report appears today in the Journal of the American Medical Association (JAMA).
“While the increased risk of autism in this study is modest, the findings add to the growing body of research showing that pregnancy is particularly sensitive period for children’s brain development,” comments epidemiologist Michael Rosanoff, Autism Speaks director for public health research.
To provide perspective, the increased autism risk seen with early gestational diabetes translated into roughly seven additional cases per 1,000 pregnancies.
“Rather than spark anxiety, the findings should underscore the importance of comprehensive prenatal care and monitoring for the health of a woman and her baby,” adds developmental pediatrician Paul Wang, Autism Speaks head of medical research.
Autism Speaks was not involved in the study, which was led by investigators at Kaiser Permanente and the University of California-Los Angeles Keck School of Medicine.
What’s the difference between increasing risk versus causing autism? Read this insightful answer by pediatric neurologist and autism expert Martha Herbert.
What we know about gestational diabetes
Gestational diabetes develops in 6 to 7 percent of pregnancies, usually during the last trimester. It often produces no symptoms. So it can easily go unnoticed unless a woman is getting regular prenatal checkups with blood tests.
The new study found no increased autism risk when gestational diabetes develops after 26 weeks of pregnancy. “It was only the less-common situation of gestational diabetes arising early in pregnancy that showed an increased risk,” Dr. Wang notes.
Autism prevalence was also higher among the children of mothers who entered pregnancy with pre-existing type 2 diabetes. However, the investigators showed that, in this scenario, the increased risk was due to other conditions associated with a mother’s type 2 diabetes. These included being an older mom or having other health conditions such as heart, lung, kidney or liver disease.
By contrast, the increased autism risk seen with early gestational diabetes remained significant even after adjusting for the mother’s age and other health conditions.
The authors propose that the lack of added risk with pre-existing diabetes may be because most obstetricians take care to control known diabetes during pregnancy. All the women in the study were enrolled in a managed healthcare plan (Kaiser Permanente) that provides comprehensive diabetes and prenatal care.
Once detected, gestational diabetes can be effectively managed. Sometimes diet and exercise are enough, according to American College of Obstetricians and Gynecologists. Sometimes medication is needed as well. (More from ACOG here.)
Broader importance of managing diabetes during pregnancy
A large body of research has shown that diabetes and related metabolic disorders during pregnancy can have long-lasting health effects on children. Studies looking specifically at maternal diabetes and autism have produced mixed results. This may be because earlier studies did not separate out the risk associated with early gestational diabetes (before 26 weeks).
“Studies such as this show us that we need big datasets and that we need to look at them carefully to understand what causes or protects against autism,” Dr. Wang concludes. “This is why Autism Speaks is working on MSSNG – the biggest data project ever for advancing understanding and treatment of autism.”
For a video segement on the study from JAMA, click here.
Dr. Wang also provided comment in a related story in USAToday here.
What we know about autism is not enough; MSSNG is the search for the answers.
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