Diabetes that develops early in pregnancy may increase women's chances of having a child with autism, according to a study published Tuesday.
The risk was seen in young children whose mothers were diagnosed with diabetes during the most crucial period of fetal brain development. Reasons for the potential link are uncertain, but it is possible that exposure to high levels of blood sugar from the mother disrupt fetal brain growth, especially in brain regions important for communication and social behavior, according to Dr. Edward Curry, a learning and behavior specialist for Kaiser Permanente in Fontana, California and co-author of the study in The Journal of the American Medical Association.
The researchers looked at medical records for more than 322,000 children born at Kaiser Permanente hospitals in Southern California between 1995 and 2010. Those whose mothers developed gestational diabetes by the 26th week of pregnancy were 40 percent more likely to be diagnosed with autism than those whose moms didn't have diabetes. Of about 3,400 autistic children, 130 were exposed to diabetes early in pregnancy.
Although the study controlled for other potential factors in children being diagnosed with autism, including obesity, the findings noted that “gestational diabetes mellitus is often accompanied by maternal obesity,” a fact underlined in the research.
In the study, youngsters whose mothers had pre-existing diabetes or developed it later in pregnancy faced no extra autism risk.
Autism refers to a spectrum of developmental disorders that typically involve problems communicating, limited social skills and sometimes intellectual difficulties or repetitive behaviors. Definitive causes aren't known, but it is thought to occur when genetic differences interact with many other factors. Previous studies have suggested these may include prenatal infections, preterm birth and parents' age
Diabetes prevents the body from making or properly using insulin, which causes sugar to build up in the blood. The study looked specifically at gestational diabetes, which develops during pregnancy and puts women at risk for future diabetes. It can be dangerous for women, and can cause preterm birth or large newborns who are at risk for diabetes later in life. Gestational diabetes is thought to affect up to about 14 percent of U.S. pregnancies.
Some previous studies linked diabetes in mothers with autism but lacked details on gestational versus pre-existing diabetes.
The authors of the new study, led by Kaiser Permanente researcher Anny Xiang, looked back at medical records that included gestational diabetes information — a research method that can only show potential links, not proof. They couldn't rule out different factors that may have contributed to autism including other prenatal problems and genetics.
A similar study published in the medical journal Pediatrics earlier this month said that children born to clinically obese women were more likely to be diagnosed with autism or developmental delays than children born to non-obese women. The University of California, Davis study of 1,004 children between two and five years old in California found that 517 were somewhere on the autism spectrum, with 48 were born to mothers with Type 2 or gestational diabetes, 111 to mothers who were obese and 148 to moms with any sort of metabolic condition, like high blood pressure.
That report came on the heels of another report from the U.S. Centers for Disease Control and Prevention that estimated every one in 88 children in the U.S. has an autism spectrum disorder. That number represents about a 25 percent increase from the agency's last report in 2006.
The findings of Tuesday's study tying diabetes and autism underscore the importance of prenatal care, including diabetes screening and treatment early in pregnancy. But the authors note that more research is needed to determine if early treatment of gestational diabetes can reduce autism risks.
Al Jazeera and wire services