Understanding Gestational Diabetes

Medical professional’s hands using a glucometer on the finger of a pregnant woman.

Gestational diabetes refers to high blood sugar that first occurs during pregnancy. Although treatable, it is associated with a higher risk of maternal high blood pressure, large-bodied babies, cesarean delivery (C-section), and low blood sugar in newborns.

About one-half of women who had gestational diabetes are diagnosed with type 2 diabetes within 10 to 20 years of their pregnancy. Children whose mothers had gestational diabetes during pregnancy are also at higher risk for obesity and for developing type 2 diabetes.

NICHD research on gestational diabetes began with a focus on ways to understand the mechanisms of gestational diabetes and to improve pregnancy outcomes. Early NICHD-funded studies identified the mechanism that increased the risk of blood sugar issues in children whose mothers had gestational diabetes. The institute also led the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study, which was conducted at 15 sites in 9 different countries. The goal of the study was to quantify how treatment for gestational diabetes affected the fetus, other pregnancy complications (such as preeclampsia), the delivery process, and health later in life. Among the findings from the HAPO study were that higher blood sugar levels were directly related to higher rates of preeclampsia, large babies, C-sections, and low blood sugar in newborns. Later studies showed that treating even mild gestational diabetes and blood sugar levels in the high-normal range improved outcomes for mom and baby.

More recently, NICHD researchers and their colleagues found that a blood test done as early as the 10th week of pregnancy may help identify women at risk for gestational diabetes. The researchers suggest that the glycated hemoglobin (HbA1c) test, commonly used to diagnose type 2 diabetes, could identify signs of gestational diabetes in the first trimester of pregnancy.

NICHD research also examines ways to prevent gestational diabetes and to reduce the risk of type 2 diabetes later in life. One such study found that women who were at a healthy body weight, ate a healthy diet, got regular exercise, and didn’t smoke before pregnancy were approximately 80% less likely to develop gestational diabetes during pregnancy, compared with those without any of these “low-risk” factors. A separate study found that excess potato consumption before pregnancy may increase the risk of gestational diabetes. Other NICHD research found that exercise could not only reduce the chances of getting gestational diabetes but also could reduce the risk of later type 2 diabetes in women who had gestational diabetes. Daily folic acid supplements, commonly taken before and in the beginning of pregnancy to reduce the risk of certain birth defects, may also reduce gestational diabetes risk.

Many of the behaviors for reducing gestational diabetes risk also reduce the risk of obesity in the children of women who had the condition.

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