Most major organ systems are formed in the growing fetus during the first seven weeks after conception. This phase -- when some women do not know that they are pregnant -- is widely considered the most critical time of development in the entire human lifespan. The early weeks of pregnancy are especially critical for women with diabetes.
The extra precautions described here mainly apply to women with diabetes who become pregnant, rather than women who develop gestational diabetes during pregnancy. During pregnancy, gestational diabetes does not carry the same risk of maternal complications as type 1 or type 2 diabetes.
How Should Women With Diabetes Prepare for Pregnancy?
Women with diabetes should have a complete physical examination before becoming pregnant. As part of the examination, they should provide their doctors with a complete medical history, including duration and type of diabetes, medications and supplements taken, and any history of diabetic complications, such as neuropathy, nephropathy, retinopathy and cardiac problems.
It is also important for women with diabetes to plan ahead and maintain excellent blood sugar control before conceiving, as high blood sugar levels during the first trimester can lead to miscarriage or congenital anomalies, which are abnormal changes during fetal development in the uterus.
Before becoming pregnant, women with diabetes should also have their kidney function tested. Although pregnancy does not worsen diabetic nephropathy (kidney disease), pregnant women with advanced kidney disease are more prone to high blood pressure, which can affect nearly all body systems and ultimately endanger the fetus.
What Special Care or Tests Are Required for Pregnant Women With Diabetes?
Pregnant women with diabetes need to carefully monitor eye care, including a full retinal examination before, during and after pregnancy, as diabetic retinopathy (damage to the retina’s blood vessels) can worsen during pregnancy. This complication occurs particularly in women who have poor blood glucose (sugar) control.
During pregnancy, women should measure their blood glucose several times daily: before and after meals, at bedtime, and at night if there is a concern about nighttime hypoglycemia (low blood sugar). The American Diabetes Association recommends pre-meal glucose measurements of 80 to 110 mg/dL (milligrams per deciliter) and post-meal glucose measurements below 155 mg/dL.
If a pregnant women with diabetes has a blood glucose measurement around 180 mg/dL, her urine should be checked for ketones (acids) to rule out ketoacidosis, which can sometimes cause a miscarriage. Ketoacidosis occurs when the body lacks insulin.
Why Is Managing Blood Sugar Especially Important for Pregnant Women With Diabetes?
In a 1989 study, women with a prepregnancy A1C value (a blood test that measures glucose levels) that was greater than 9.3% had the highest risk of miscarriages and birth to babies born with congenital anomalies. Studies have indicated that A1C values of up to 6% (with 5% being considered normal) carry the same risk of miscarriage and fetal anomalies as a nondiabetic pregnancy.
Women with higher than normal blood sugar levels, whether they have gestational, type 1 or type 2 diabetes, also tend to have larger babies. This leads to a greater risk of injuries of the shoulder and brachial plexus (the nerves connecting the spine with the arm and shoulder) to the infant during childbirth.
Poorly controlled diabetes is also associated with pre-eclampsia (high blood pressure) and premature delivery.
There is very little information about the effect of hyperglycemia (high blood sugar) on long-term development of the fetus.
Are There Diabetes Medications That Should be Avoided During Pregnancy?
Women with type 2 diabetes who take oral medications for blood sugar control should switch to using insulin before becoming pregnant and throughout pregnancy. While some oral antidiabetic medications have been studied and were found to be safe in pregnancy, insulin is the best and safest method for controlling blood sugar throughout pregnancy.
Many blood pressure medications can be dangerous for the fetus; therefore, usually these medications should be stopped before pregnancy if blood pressure can be maintained below 130/80 mmHg with dietary salt control alone. If blood pressure medications are absolutely necessary, women may have to be switched to a new medication prior to pregnancy. In particular, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are excellent for blood pressure control in nonpregnant women with diabetes; however, these are not safe when used by a woman who is diabetic and pregnant. Similarly, cholesterol-lowering medications should also be stopped during pregnancy.
How are Diet and Exercise Managed for Pregnant Women With Diabetes?
Nutrition is vitally important for pregnant women with type 1 and type 2 diabetes. In general, pregnant and nursing women with diabetes should ingest 15 to 17 calories per pound of body weight daily, although this may vary from person to person and should be discussed with the diabetes care team before, during, and after pregnancy and nursing.
Important nutritional concerns in type 1 diabetes include consistent day-to-day food intake and consumption of a bedtime snack, and adjusting insulin according to activity and food content to prevent high or low blood sugar levels to carefully treat hyperglycemia and hypoglycemia, respectively.
Nutrition is the most important means of blood glucose control in type 2 diabetes. Pregnant women with type 2 diabetes should talk with their diabetes care providers, and ideally a diabetes nutritionist, to determine their goals for daily calories, carbohydrates, nutritional balance in foods, and timing of eating throughout the day.
Exercise is beneficial for pregnant women with type 2 diabetes, as it helps improve the body’s response to insulin. Women with type 1 diabetes who exercised prior to pregnancy can probably continue to exercise during pregnancy. However, women with type 1 diabetes who are not accustomed to exercise are more prone to hypoglycemia with exercise during pregnancy; for this reason, these women are not advised to begin an exercise regimen when pregnant.