Study links gestational diabetes to lower childhood IQ and higher risks of autism and ADHD

A large systematic review presented at the European Association for the Study of Diabetes annual meeting found that gestational diabetes is associated with measurable reductions in childhood cognitive scores and higher risks of developmental disorders, including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).

The analysis, which pooled observational studies through April 2024 and encompassed data from more than 9 million pregnancies worldwide, reported that children born to mothers who experienced high blood sugar during pregnancy scored on average about four points lower on overall IQ tests and more than three points lower on measures of verbal crystallized intelligence than children not exposed to the condition. The review also found a 45 percent higher risk of total and partial developmental delays, a 36 percent increased risk of ADHD, and a 56 percent higher risk of ASD among exposed children.

Researchers said several biological mechanisms could explain the associations, including inflammation, cellular stress, reduced oxygen delivery to the fetus, elevated insulin and altered nutrient supply in the womb. Those processes, investigators warned, may disrupt critical stages of fetal brain development and later translate into differences in learning, verbal reasoning and behavior.

"There are increasing concerns about the neurotoxic effects of gestational diabetes on the developing brain," said Dr. Ling‑Jun Li, lead author of the review and an assistant professor at the National University of Singapore School of Medicine. "Our findings underscore the urgency of addressing this significant public health concern that poses substantial cognitive dysfunction risks for both mothers and offspring."

Gestational diabetes mellitus (GDM) typically emerges in the second or third trimester, when placental hormones can cause maternal insulin resistance. If the mother’s pancreas cannot produce enough insulin to meet increased demands, blood glucose rises. The condition usually resolves after delivery but can have lasting consequences for both mother and child if not identified and managed.

GDM affects a sizable and growing share of pregnancies. In the United States, it is estimated to affect around nine percent of pregnancies, translating to hundreds of thousands of pregnancies each year. Public health experts attribute the upward trend to higher maternal age and rising obesity rates, which are also drivers of the broader diabetes epidemic.

Because gestational diabetes often produces no obvious symptoms, standard prenatal care includes proactive screening. The two-step screening approach commonly used in the United States involves an initial glucose challenge test around 24 to 28 weeks of gestation, followed by a multi-hour oral glucose tolerance test for women who exceed the initial threshold. Early identification allows clinicians to initiate diet and exercise interventions and, when necessary, medication or insulin to control blood sugar during pregnancy.

The review drew on observational studies of varied design and geographic settings; the authors noted that heterogeneity in how gestational diabetes is diagnosed and in outcome measurement complicates comparisons across studies. Nevertheless, the pooled estimates were statistically significant across multiple cognitive and developmental outcomes.

Clinicians and researchers stressed that while associations were observed, the studies reviewed do not prove a direct cause-and-effect relationship and that more research is needed to clarify biological pathways and potential interventions. The authors called for standardized diagnostic criteria, longer-term follow-up of exposed children, and studies designed to test whether tighter glucose control during pregnancy can reduce neurodevelopmental risks.

Current clinical guidance emphasizes prevention and management: women planning pregnancy are advised to achieve a healthy weight and control blood sugar when possible, and pregnant women are counseled on nutrition, physical activity and regular prenatal screening. Known risk factors for gestational diabetes include prior GDM, a history of delivering a large baby, overweight or obesity, family history of type 2 diabetes, polycystic ovary syndrome, and certain racial and ethnic backgrounds.

The findings add to a growing body of evidence linking maternal metabolic health during pregnancy with long-term outcomes for offspring and highlight the potential importance of maternal glycemic control as part of prenatal care strategies aimed at improving child cognitive and developmental outcomes.