The babies of women with diabetes are two to five times more likely to develop birth defects than the offspring of women without the disease.
A recent study by Joslin Diabetes Center scientists suggests that high blood glucose levels early in pregnancy deprive the embryo of oxygen, interfering with its development. The research appears in the October issue of the American Journal of Physiology: Endocrinology and Metabolism.
Women with both type 1 and type 2 diabetes run a high risk of having babies with birth defects, especially of the heart and spinal cord. Because these organs form during the first few weeks of pregnancy, coinciding with the time that a woman may first learn that she is pregnant, aggressive control of blood glucose levels just before and after conception is critical.
The study’s lead investigator, Dr. Mary R. Loeken, Ph.D., recommends that obese women who don’t know if they have diabetes but who are planning to become pregnant be tested for diabetes. “Many obese women have type 2 diabetes and do not know it, so it is a good idea to bring glucose levels to within the normal range before becoming pregnant, and to monitor women with pre-diabetes closely during pregnancy to make sure they don’t develop diabetes,” Dr. Loeken says.
In the new study, Dr. Loeken and her colleagues examined embryos of pregnant mice injected with glucose (the sugar that is elevated in blood during diabetes) to mimic diabetic pregnancy. They found that the oxygen concentrations in embryos of mice injected with glucose were significantly lower than in the control embryos, and that embryos from pregnant mice with high blood glucose levels had an eight-fold increase in a severe type of birth defect called neural tube defects.
Neural tube defects occur when parts of the brain, spinal cord, or their protective coverings fail to develop properly. Neural tube defects and heart abnormalities are the most common birth defects affecting babies born to women with diabetes.