Most babies are born healthy. Approximately 3% to 4% however, are born with a type of birth defect. This percent is considered the background rate for birth defects in the general population.
There are many reasons why birth defects occur. The majority are due to multifactorial inheritance, which is a combination of environmental and genetic factors. However, 30% of birth defects have a known cause, such as: chromosome abnormalities, single gene defects, or exposure to an agent that can disturb early development (also called a teratogen).
Diabetes, including type 1 and type 2, can increase a woman’s risk for a pregnancy to be affected with certain birth defects, particularly heart defects, open neural tube defects (such as spina bifida), kidney defects, and abnormal development of the lower spine. In fact, the risk for these birth defects is 6-10%, twice as large as the background risk. Diabetes can also increase a woman’s risk for adverse pregnancy outcomes, a term that includes the chance for miscarriage, stillbirth, preterm delivery, large baby size and neonatal breathing issues or low blood sugar.
Because of the increased risk associated with maternal diabetes during pregnancy, your physician may recommend a detailed ultrasound between 18-20 weeks gestation and a fetal echocardiogram during any pregnancy. Both procedures are non-invasive, thus they pose no risk of harming a baby. An ultrasound takes an overall look at fetal development. Fetal echocardiograms, done later in pregnancy, focus on the development of the baby’s heart. Follow up ultrasounds and biophysical testing (BPP) may also be warranted. A BPP is another non-invasive test that assesses a baby’s heart rate, muscle tone, movement, breathing and the amount a amniotic fluid present.
If you have diabetes, the best time to control your blood glucose, also called blood sugar, is before you get pregnant. Research has shown that when women with diabetes keep blood glucose levels under control before and during pregnancy, the risk of birth defects is reduced to the background rate.
For more information on diabetes and pregnancy, visit The National Institute of Diabetes and Digestive and Kidney Diseases website.