Ask the experts – Diabetes and pregnancy

Guest Expert: Florence Brown, MD, is co-director, Joslin-Beth Israel Deaconess Medical Center Diabetes and Pregnancy Program, and an instructor in medicine at Harvard Medical School.

Q. What can women with diabetes do to help ensure a healthy pregnancy?

A. Women can reduce their risk of complications by doing the following: meeting regularly with a healthcare provider who has experience treating pre-existing diabetes in pregnancy to establish preconception treatment goals; scheduling an eye exam to evaluate whether their eyes are stable enough for pregnancy and following up as recommended by their ophthalmologist; keeping regularly scheduled prenatal appointments so mother and baby can be monitored closely; taking prenatal multivitamins daily; and checking blood glucose levels before driving.

Q. What special health risks do pregnant women with pre-existing diabetes face?

A. Pregnancy can pose risks for both the fetus and the mother. If a mother’s blood glucose is not tightly controlled, her infant will be at higher-than-average risk of developing birth defects. If a woman’s hemoglobin A1C, a measurement of blood glucose control reflecting the average blood glucose for the past 60 to 90 days, is under 7%—or as close to 6% as possible—the risk of birth defects is approximately 2%. If her A1C is above 10%, the risk of birth defects soars to between 30% and 40%. Birth defects that involve the heart, kidneys, brain, and spinal cord can develop during the first three to six weeks following conception.

While in utero, infants of women with diabetes are also at risk for excessive weight gain. It is usually a good idea to check the fetus’ [abdominal] circumference on ultrasound several times during the third trimester to monitor the baby’s size, in case steps need to be taken to control the mother’s blood glucose more tightly.

Q. Do some pregnant women have problems with low blood glucose?

A. Yes. Pregnant mothers are at increased risk of having severely low blood glucose. This is especially true for women who do not sense when their blood glucose is low or who have had a severe reaction in the past year. This may occur in up to 40% to 45% of pregnancies because women are trying to keep their blood glucose levels in the normal range. This can happen even when women are checking their blood glucose frequently. It is important that pregnant women always test their blood glucose before driving because of this danger. On the other hand, pregnancy can also increase the risk of a complication called diabetic ketoacidosis (DKA). Women need to check their urine ketones if they have blood glucose above 200 mg/dL or if they feel sick, and they should contact their healthcare provider to assist them with immediate initiation of treatment.

Women who have beginning eye changes from diabetes, called diabetic retinopathy, are at increased risk to worsen those changes. Periodic dilated eye exams are needed to monitor this complication during pregnancy.

Women with diabetes are also at higher risk of developing pregnancy complications related to high blood pressure or pre-eclampsia (high blood pressure and protein in the urine). This may require early delivery of the infant. Blood pressure and urine testing for protein must be watched closely.

Q. Is the risk greater for women with type 1 or type 2 diabetics during pregnancy?

A .The risks of pregnancy are similar except that women with type 1 are at risk for DKA, which is not a risk for women with type 2 diabetes. DKA is a condition caused by the unregulated breakdown of fat that occurs when insulin levels are very low or absent. It leads to high levels of ketone bodies in the blood, which make the blood acidic. People with type 2 diabetes have higher insulin levels than patients with type 1 diabetes but are resistant to the effects of insulin, thus explaining why their blood glucose levels are high. However, these higher circulating levels of insulin are adequate to prevent uncontrolled fat breakdown and to keep them from developing DKA.