- Kenny Lin, MD, MPH
A recent report from the Centers for Disease Control and Prevention documented a precipitous rise in the rate of gestational diabetes in the U.S. from 2016 to 2020, based on data collected from birth certificates. In 2020, gestational diabetes affected 7.8% of all pregnancies, reflecting a 13% increase since 2019 and a 30% increase since 2016. Prevalence increased with increasing age (2.5% in patients younger than 20 years and 15.3% in those aged 40 or older) and increasing pre-pregnancy body mass index (BMI). Both factors are likely driving the overall rise in gestational diabetes; the median age at which U.S. women gave birth reached an all-time high of 30 years in 2019 and only 2 in 5 women with a live birth in 2020 had a normal BMI prior to pregnancy.
The U.S. Preventive Services Task Force (USPSTF) recommends screening for gestational diabetes in asymptomatic pregnant patients at or after 24 weeks of gestation. Although the USPSTF did not identify a preferred test, a previously discussed study suggested that the two-step approach (a non-fasting 50 gram oral glucose challenge test followed by a fasting 100 gram glucose tolerance test if the first test is positive) "produces equivalent benefits, and fewer harms, than the one-step approach."
Adverse outcomes associated with gestational diabetes include gestational hypertension, preeclampsia, shoulder dystocia, macrosomia, and Cesarean delivery. Gestational diabetes also confers a 7-fold greater maternal risk of developing type 2 diabetes later in life and 1.5 times greater risk of the child being overweight in childhood or adolescence. Management of gestational diabetes begins with glucose self-monitoring and lifestyle modifications, followed by oral medication or insulin if target blood glucose levels are not achieved.Prevention of gestational diabetes includes counseling on appropriate weight gain goals based on pre-pregnancy BMI, which can generally be achieved by averaging "350 to 450 calories per day above the previous intake (e.g., two slices of bread with half an avocado, ¾ cup of Greek yogurt or 1 cup of blueberries with two hard-boiled eggs)." Additionally, "patients should be encouraged to engage in moderate aerobic activity most days of the week for at least 20 to 30 minutes at a time, for a total of at least 150 minutes per week." In a previous AFP Community Blog post, Dr. Erin Fredrickson discussed strategies for facilitating exercise in pregnant patients. The USPSTF recommends offering behavioral counseling interventions for healthy weight and weight gain in pregnancy; effective interventions generally started at the end of the first trimester and varied in duration and intensity (from 15 to 120 minutes and from 1 to more than 12 total contacts).