Among the most common complications of pregnancy is a high level of glucose in the blood, a condition known as gestational diabetes mellitus (GDM). GDM is not a serious condition as it usually disappears after birth. However, the excessive sugar can often lead to large, difficult-to-deliver babies. Cuilin Zhang, a clinical epidemiologist at the National University of Singapore, says that GDM was not considered a serious disease for a long time. Multiple studies, including one by Zhang, have shown that the condition is linked to long-term diabetes risk for the mother and obesity for the child.
This summer the first-ever national analysis of trends in gestational diabetes conducted by the Centers for Disease Control and Prevention brought alarming news. Between 2016 and 2020 the prevalence jumped 30 percent, affecting nearly 8 percent of U.S. pregnancies in 2020. A rise in prevalence was expected, according to Elizabeth Gregory, a CDC scientist and coauthor of the report. “We know that risk factors such as obesity and older maternal ages have been increasing over the past few decades.” This affected nearly 8 percent of U.S. pregnancies in . What was unexpected was a giant jump in a single year: GDM was up 13 percent in 2020, as opposed to about 5 percent in each of the previous four years.
The CDC report did not examine the reasons for the 2020 surge, but the COVID pandemic is an obvious culprit. Gregory points out that gestational diabetes can be affected by decreased physical activity, weight gain, and other lifestyle factors during lockdowns. An Italian study of 1,295 women, published earlier this year, supports this idea. The study found that GDM incidence nearly tripled during lockdown periods, rising from 3.4 percent to 9.3 percent prelockdown. Pregnancy weight gain averaged 20.5 pounds during Italy’s strict lockdowns versus 14.5 pounds prepandemic. Higher body mass index (BMI), was associated with greater risk.
Zhang suggests that other contributing factors could include a poor diet, more snacking, less fresh produce, stress, inability to exercise, and depression. Work by Zhang and her former colleagues at the National Institutes of Health showed that depression is associated with a higher risk of GDM, particularly in nonobese women.
The CDC analysis showed that gestational diabetics were more common in women who are not overweight than those who have a high BMI. Those of non-Hispanic Asian origin had by far the highest incidence (14.9 percent); non-Hispanic Black women had the lowest (6.5 percent). Asian people in general tend to develop type 2 diabetes–a form in which the body does not use insulin effectively–at a lower BMI than do people of other ethnicities, and the same appears to be true with gestational diabetes. Zhang recently moved to Singapore to lead the university’s new Global Center for Asian Women’s Health.
Women who have gestational diabetes are at seven times the risk of developing type II diabetes later in their lives. They also have a higher chance of developing cardiovascular disease. It is unclear if GDM causes these conditions or if those who are more susceptible to GDM also have an underlying vulnerability for type 2 diabetes and heart disease. The baby is at risk of birth injury due to his or her large size. There is also a higher risk of obesity and impaired glucose tolerance.
Zhang has shown that early intervention can reduce the risk of gestational diabetes. A 2016 study done in Finland, for example, found that a healthy diet and exercise regimen during pregnancy cut the incidence of GDM by 39 percent among participants who had a history of the ailment or who were obese. This suggests that it is best to start such a program early in pregnancy, or even before you become pregnant. Most pregnant patients are not tested for diabetes before the sixth or seventh months. Those with obesity or other risk factors are supposed to be screened much earlier, but that recommendation may not be widely followed by physicians, says obstetrician-gynecologist Veronica Gillispie-Bell of Ochsner Health Center-Kenner in New Orleans.
For low-income women, “pregnancy could be their first chance to find out if you have diabetes,” Gillispie-Bell says. She leads Louisiana’s efforts in reducing its high maternal mortality rate. GDM is a new factor in the ongoing crisis in maternal health and reproductive health.