Gestational diabetes is a form of glucose intolerance that can develop during pregnancy. It poses serious health risks for both the mother and the baby, including an increased risk of heart disease and diabetes.

Even more mothers and babies are likely to develop the condition, according to the findings of a study led by researchers at Northwestern University Feinberg School of Medicine. It found that rates of gestational diabetes in the U.S. had increased by 36 percent during the nine-year period between January 1, 2016 and December 31, 2024.

The work updates the team's earlier research which looked at rates of gestational diabetes between 2011 and 2019 and confirms almost 15 years of steady increases. “Gestational diabetes has been increasing for more than 10 years, which means that whatever we are doing to combat diabetes during pregnancy is not working,” Nijay Shah, senior author on the study, said in a statement.

Rates of gestational diabetes in the U.S. increased by 36 percent over nine years.

The researchers think gestational diabetes rates have been increasing as certain risk factors, such as older maternal age and higher rates of overweight, obesity and hypertension, have also been rising, Emily Lam, first author on the study, said in an email.

“The health of young adults has been worsening, with less healthy diets, less exercise and more obesity,” said Shah, an assistant professor of cardiology at the Feinberg School of Medicine who studies health complications during pregnancy such as gestational diabetes and high blood pressure and ways to prevent them. “These trends may underlie why rates of gestational diabetes have increased,” he explained.

The study period included the COVID pandemic, so people might not have seen their provider as often as needed. They also may not have been eating as well or had less access to nutritious foods.

The researchers analyzed birth certificates for babies born to 12.6 million first-time mothers between the ages of 15 and 44 from National Center for Health Statistics. About 52 percent of mothers identified as white, almost 23 percent identified as Hispanic, 13 percent as Black, more than seven percent as Asian, 0.6 percent as American Indian or Alaskan Native and 0.2 percent as Native Hawaiian or Pacific Islander.

“The health of young adults has been worsening, with less healthy diets, less exercise and more obesity.”

They found Hispanic women had 85 cases of gestational diabetes for every 1,000 births; white women had 71 cases; and Black women had 67 cases.

Rates of gestational diabetes increased across every group during the study period, but they increased the most among those who were American Indian or Alaskan Native (137 cases for every 1,000 births), Asian (131 cases) or Native Hawaiian or Pacific Islander (126 cases).

Because these groups are often underrepresented in research, it's not yet clear why their rates of gestational diabetes are so high, Lam, a medical student at Feinberg, explained. Social and cultural factors — such as diet, access to reliable healthcare and cultural patterns related to pregnancy — may have contributed to the increase in gestational diabetes seen among the three groups, she added.

The study is published in JAMA Internal Medicine.