Exercise Reduces the Risk of Diabetes of Pregnancy

How can women reduce their risk of having diabetes that begins during pregnancy? The question is an important one, since the risk of so-called gestational diabetes mellitus has risen significantly over the last 15 years. The problem for the mother is that she has a greater risk of having prediabetes and Type 2 diabetes after the baby is born. The problem for the baby is that he or she has a greater risk of obesity, prediabetes and Type 2 diabetes in the young adult years. Until recently, little was known about how to reduce the risk of this serious complication of pregnancy.(1)

Researchers at Harvard have now provided some clarification.(1) They looked at data from the Nurses' Health Study II, which began in 1989 and involved a total of 116,671 women ages 24-44 years. From these women, they selected a group who had never had diabetes or gestational diabetes, cancer, or heart disease, and who were not pregnant when the study began in 1989. Only women who had single births during the study period were included in the final analysis; the final number enrolled in the study was 21,765.

Both physical activity and sedentary behaviors were assessed prior to pregnancy by means of questionnaires at the study inception and then two additional times over ten years. Women were asked how many hours per week they spent in such vigorous activities as jogging, lap swimming, tennis, as well as less vigorous activities such as walking or hiking. The amount of time spent in sedentary activity such as sitting at meals or at a desk was also assessed. The number of MET (metabolic equivalent) hours per week was calculated for each woman.

The researchers found that the more active a woman was, and the more vigorous activity she pursued, the less was her risk of diabetes during pregnancy. The findings were true for women both with and without a family history of diabetes, as well as for various categories of body mass index (normal weight, overweight or obese). Among walkers and hikers, women who walked four or more hours per week at a brisk or very brisk pace had the least risk of diabetes during pregnancy. Alternately, women who spent 20 hours or more per week watching television without engaging in other vigorous activity had a two times greater risk of developing diabetes of pregnancy. The authors conclude that an active lifestyle for women of reproductive age is likely to have potential health benefits.(1)

Anyone who contemplates beginning an exercise program should seek the advice of their physician.

(1) Zhang C, Solomon CG, Manson JE and Hu FB. A prospective study of pregravid physical activity and sedentary behaviors in relation to the risk for gestational diabetes mellitus. 2006 Arch Intern Med 166: 543-548.