NEW YORK - Babies born to poor mothers with pregnancy-related diabetes have an extra-high risk of developing attention-deficit/hyperactivity disorder, a new study suggests.
So-called gestational diabetes typically develops during the second or third trimester of pregnancy, especially in women who are overweight before getting pregnant, eat an unhealthy diet and don't exercise. It affects between two and 10 percent of pregnant women, according to national data, and rates are rising alongside type II diabetes in the general public.
While the new study doesn't prove that moms' gestational diabetes leads to ADHD in kids, it's likely that diabetes-related changes in the blood shared by mother and fetus could affect how babies' brains develop, researchers said.
"There seems to be more research going in the direction that... the brains of children with ADHD are different," said Ginette Dionne, who has studied gestational diabetes and language development at Laval University in Quebec but wasn't involved in the new study.
"Gestational diabetes may not be a specific cause (of ADHD), but may be one of the factors that affects brain development," she added.
Researchers from the Mount Sinai School of Medicine in New York led by Dr. Yoko Nomura recruited 212 preschoolers for their study, two-thirds of whom were at risk for ADHD, based on teacher and parent reports.
According to interviews with their moms, 21 had been diagnosed with gestational diabetes while pregnant.
The researchers found that at ages three to four, kids whose mothers had had gestational diabetes scored worse on tests of language, memory and IQ than those with diabetes-free moms. And at age six, they had more communication and attention problems.
The effect seemed to be most pronounced in kids born to moms with gestational diabetes who were also poor. Those kids were 14 times more likely to meet the criteria for an ADHD diagnosis at age six, compared to kids of moms who were middle class or well-off and hadn't had gestational diabetes.
Babies of women who'd had gestational diabetes but weren't poor, or were poor but diabetes-free, were not at increased risk of ADHD, the researchers report in the Archives of Pediatrics & Adolescent Medicine.
In cases of gestational diabetes, babies get exposed to extra glucose in the blood that passes through the placenta, researchers said. Diabetes could also affect the amount of oxygen or iron in that blood.
Something about the altered blood, or the way the baby's body responds to it, may interfere with brain development.
"Really right now we have no idea what the specific culprit is," Dionne told Reuters Health.
"What the cumulative data is showing is there is something happening to the brain development of babies of these mothers that have gestational diabetes, and it doesn't seem to affect all babies equally."
Environment after birth also appears to play a role -- kids who grow up in disadvantaged families might not be able to bounce back from early developmental issues, according to experts.
"If you have a subtle problem, if you have better medical care, better food, better intellectual stimuli, you might be able to fix it," Nomura told Reuters Health.
"But if you're born into a harsher, more adverse environment, maybe that tiny little problem acts as a bigger hindrance developmentally."
Researchers agreed that the findings reinforce the importance for women who are planning to become pregnant of getting their weight under control and improving their diet to lower their chances of developing gestational diabetes.
"It is equally important not to frighten pregnant women because (gestational diabetes) is relatively common," said Asher Ornoy, who studies the effects of gestational diabetes at the Hebrew University of Jerusalem, Israel, in an email to Reuters Health.
"Hence preventive measures -- early diagnosis, good nutrition in pregnancy, avoiding overweight... are very important."