Gestational diabetes linked to higher autism risk, study suggests; UK doctors call for broader screening

A landmark review of 48 studies, involving more than nine million pregnancies, found that women who develop gestational diabetes are about 60 percent more likely to have a child diagnosed with autism. The blood-sugar disorder, which is often symptomless and linked to obesity and older mothers, is a growing concern for researchers trying to explain a rise in neurodevelopmental conditions. The study, presented at the European Association for the Study of Diabetes, notes that there is no single cause of autism and that the disorder emerges from a mix of genetics and environmental influences.

In addition to autism, the review found that children of mothers with gestational diabetes were 36 percent more likely to be diagnosed with attention deficit hyperactivity disorder, or ADHD. It also found that exposure in the womb raises the chances of foetal macrosomia, or “giant baby syndrome,” which can complicate delivery and carries longer-term health risks. The condition now affects at least one in 20 expectant women in many populations.

Experts caution there is no simple causation; gestational diabetes reflects a mix of genetics, maternal health, and environment. Some researchers say that while the data point to a link between maternal blood sugar and later neurodevelopmental outcomes, the risk is likely driven by a broader set of factors. The review represents one of the clearest signals to date that lifestyle-related factors during pregnancy may contribute to autism risk, potentially offering opportunities for prevention.

NHS testing guidelines in the UK do not screen all pregnant women for gestational diabetes. Currently, a glucose tolerance test is offered at around 24 to 28 weeks to those considered at risk, such as women with a body mass index above 30 before pregnancy, a previous baby weighing more than 4.5 kilograms, a family history of diabetes, or certain ethnic backgrounds including Chinese, South Asian, African-Caribbean, and Middle Eastern origins. Some experts say screening should start earlier, at 16 to 18 weeks, or be expanded to include more high-risk patients, but resource limits mean many high-risk women still go untested.

Dr. Dimitrios Siassakos, professor of obstetrics at University College London, called the rate of undiagnosed gestational diabetes a serious problem. He said the study did not examine how many of the mothers had gestational diabetes, and that higher infection risk associated with diabetes can lead to fever treated with paracetamol, a factor that some have argued could link painkiller use with autism. He added that when pregnancy conditions co-occur, it is important to consider gestational diabetes as a possible underlying driver rather than attributing risk to a single medication.

Tests used to diagnose gestational diabetes are themselves imperfect. The standard oral glucose tolerance test requires fasting and a two-hour post-drink blood draw, but evidence suggests the two-hour threshold may miss cases, particularly early in pregnancy. Siassakos argues that testing after one hour could improve detection, and that earlier diagnosis is crucial because early treatment reduces risks to both mother and child. He notes that "the best way to prevent the complications of gestational diabetes is to stop it from developing in the first place," emphasizing prevention as a public-health priority.

Case anecdotes illustrate the diagnostic challenges. Estella Newbold-Brown, a 43-year-old in London, gave birth to twins five years ago after a pregnancy with intermittent diabetes symptoms. A 24-week test suggested no diabetes, but a later test revealed elevated sugar levels. She describes a difficult pregnancy with pre-eclampsia, and one child born larger than average. Her experience underscores concerns that many high-risk women may be missed by current screening practices and that timely diagnosis can influence management and outcomes.

Experts say that once gestational diabetes is diagnosed, lifestyle interventions are powerful. Four to five hours of moderate exercise weekly, such as brisk walking, along with a diet rich in fiber and low in refined carbohydrates and saturated fats, can reduce blood sugar levels and limit complications. Some pregnant women may need medication, but even for those with diabetes, such changes can yield significant benefits for both mother and baby. Doctors caution that prevention is preferable to treatment, noting that avoiding the condition altogether remains a public-health goal.

The concern over large babies feeds into a broader social interest in macrosomia, sometimes celebrated online as a sign of healthy pregnancy. The hashtag trend has drawn millions of views, with posts showing infants who weigh well above average at birth. Experts say that untreated gestational diabetes increases the likelihood of macrosomia, which in turn can raise the risk of shoulder injuries at delivery, stillbirth, and obesity or diabetes later in life for the child.

Looking ahead, health researchers warn that diabetes and related conditions will remain a growing public health challenge. Diabetes UK has projected that the number of people with diabetes in the UK could rise by roughly 40 percent by 2035, to about 6.2 million. In the meantime, officials stress that improving screening, expanding prevention efforts, and supporting expectant mothers with risk factors could reduce both premature deliveries and long-term health outcomes.

The topic remains controversial for some, including critics of broad attribution of autism risk to maternal conditions. Still, researchers emphasize that the study’s message is not to blame mothers, but to identify potential, preventable factors that could lower risk when addressed early and with appropriate support.