When mothers develop diabetes during the first 26 weeks of pregnancy, the child they’re carrying may be at increased risk of autism, according to a new study.
Kids exposed to so-called gestational diabetes before the third trimester were at higher risk compared to those whose mothers did not develop diabetes during pregnancy, developed it later in pregnancy or had type 2 diabetes before pregnancy, researchers found.
Many factors have been associated with autism, so it is not surprising that gestational diabetes may be added to the list, lead author Anny H. Xiang of Kaiser Permanente Southern California in Pasadena told Reuters Health by phone.
“Clearly this was an observational study and you really cannot draw a causal association,” she added.
Gestational diabetes, but not preexisting type 2 diabetes, was tied to autism risk, which is a new finding, Xiang said.
Gestational diabetes usually emerges in the middle of pregnancy for women who did not have diabetes before becoming pregnant. It can often be managed with diet and exercise and will go away soon after delivery, according to the U.S. Centers for Disease Control and Prevention.
Xiang and her co-authors studied data on more than 322,000 children born in Kaiser Permanente Southern California hospitals between 1995 and 2009.
About two percent of the children were born to mothers diagnosed with type 2 diabetes before pregnancy, almost eight percent were exposed to gestational diabetes and 90 percent were not exposed to any maternal diabetes.
More than half of mothers with type 2 diabetes and a quarter of those with gestational diabetes used antidiabetic medications during pregnancy.
Overall, through early childhood, nearly 3,400 of the children were diagnosed with autism spectrum disorder (ASD).
Gestational diabetes diagnosed before six and a half months of pregnancy was tied to later autism risk, even after accounting for family history of ASD and maternal smoking, pre-pregnancy height and weight and gestational weight gain, the authors reported in JAMA.
Kids whose mothers had gestational diabetes earlier in pregnancy were about 42 percent more likely to be diagnosed with autism than those who whose mothers had no form of diabetes.
Type 2 diabetes also seemed to be linked to a higher risk of autism, but the association was explained by factors like maternal age and other health problems, the authors write.
“If you know you have diabetes already, then you are already under the care of a doctor and you may be more constantly monitored,” Xiang said.
But a woman who is diagnosed with gestational diabetes, especially earlier in pregnancy, may have had high blood sugar to begin with and not realized it, she said.
The authors suspect that some children in the gestational diabetes group may have been exposed to untreated high blood sugar during early critical brain development.
“I think we are starting to learn more and more about the potential effects of the intrauterine environment on long term outcomes in the offspring,” said Linda Dodds of Dalhousie University in Halifax, Nova Scotia. Dodds studies the impact of environmental, genetic and medical factors during pregnancy.
Polycystic ovary syndrome, high blood pressure, high cholesterol and older maternal age are all risk factors for gestational diabetes, she said.
“Future studies directly linking maternal glucose levels during early and late pregnancy with (autism) risk, including imaging studies of infant and childhood brain development by MRI are needed to provide evidence for a true causal relationship,” said Dr. Dana Dabelea of the University of Colorado Denver, who also was not part of the new study.
“No matter whether we found this or not, the overall advice to pregnant women is go see doctor, check your blood sugar, make sure it’s normal,” Xiang said. “Studies have also shown that a mother who had gestational diabetes is more likely to have increased risk for obesity and diabetes in the future.”
Encouraging a healthy pregnancy is always good advice, but there can be no direct recommendations based on this study, Dodds told Reuters Health by email.
“Since we do not know whether there is a causal relationship between gestational diabetes and autism, we don’t know if earlier, or more aggressive management, would have any effect on autism risk,” she said.
“This is one study, we need more studies to confirm it,” Xiang said.