Pregnancy :: Fetus at risk at lower levels of maternal blood glucose

Gestational diabetes may place a much higher percentage of pregnant women – and their unborn babies – at risk for adverse outcomes than previously believed, according to a major international study presented at the American Diabetes Association’s 67th Annual Scientific Sessions.

“We found that the risk of having a large baby, a first-time Cesarean delivery, low blood glucose levels in the newborn requiring treatment, and high blood insulin levels in the baby that may signal problems ahead, all increased as the mother’s blood glucose level during pregnancy increased,” said Boyd E. Metzger, MD, Professor of Medicine, Division of Endocrinology, Northwestern University Feinberg School of Medicine, Chicago, and Principal Investigator of the study, in a recent interview.

“These relationships were continuous over the entire range of blood glucose levels found in over 23,000 pregnancies, even in ranges previously considered to be within the normal range for pregnant women.” Nonetheless, the higher the mother’s blood glucose, the higher the risk that these problems will occur.

The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study was a seven-year international study that recruited approximately 25,000 pregnant women at 15 centers in 9 countries to achieve a major advance in knowledge on levels of blood glucose during pregnancy that place the mother, fetus, and newborn at increased risk for adverse outcomes.

Ultimately, 23,325 women completed the study. HAPO was a basic epidemiologic investigation designed to clarify unanswered questions on the association of various levels of glucose intolerance during the third trimester of pregnancy and risk of adverse outcomes.


Nearly 21 million Americans have diabetes, a group of serious diseases characterized by high blood glucose levels that result from defects in the body’s ability to produce and/or use insulin. Diabetes can lead to severely debilitating or fatal complications, such as heart disease, blindness, kidney disease, and amputations. Diabetes is the fifth leading cause of death by disease in the U.S.

Pregnant women who have never had diabetes before but who have high blood glucose levels during pregnancy are said to have gestational diabetes (GDM). GDM affects about 4% of all pregnant women – about 135,000 cases of gestational diabetes in the United States each year.

The study was supported by grants from the National Institutes of Health and the American Diabetes Association.