Pregnancy and Diabetes
Diabetes is one of the most common complications of pregnancy, affecting 2 to 10% of all pregnancies. Diabetes is a medical condition that leads to increased blood glucose levels, the sugar that acts as the body’s main source of fuel. More than nine million women in the United States have diabetes and one third of these women are not aware that they have diabetes. When pregnant diabetic women are managed using an integrated team approach, the risk of complications for the patient and her baby are similar to nondiabetic women. This article presents information for pregnant patients with preexisting and gestational diabetes.
Three Types of Diabetes
Three types of diabetes exist; type I (juvenile onset, insulin dependent), type II (adult onset, non-insulin requiring), and gestational diabetes that is usually limited to pregnancy. In type I diabetes the body’s pancreas cannot produce enough insulin, the main hormone that controls blood glucose levels. Patients with type I diabetes often develop symptoms of weight loss despite of increased eating, increased thirst, and excessive urination. Type I diabetes usually develops early in life and patients require insulin injections to maintain normal glucose levels. Type II diabetes tends to develop later in life and is often without symptoms, explaining why one third of women may not know that they have diabetes. In type II diabetes, the pancreas produces insulin but the body does not respond enough to the insulin; that is the body becomes resistant to insulin. Patients with Type II diabetes can often control their blood sugar levels by altering their diet, increasing their activity, and losing weight; but in some cases oral medications or insulin may be necessary. Gestational diabetes is diabetes first recognized at any time during the pregnancy, even if there are strong suspicions that it existed prior to the pregnancy. Gestational diabetes occurs because the placenta (afterbirth) produces hormones that make the body resistant to insulin and the pancreas cannot produce enough insulin to overcome this resistance. Similar to type II, patients are usually without symptoms. Of pregnant patients with diabetes, 4% have type I, 8% have type II, and the remaining 88% have gestational diabetes.
Women with Prepregnancy Diabetes
Women with known type I or II diabetes should receive prepregnancy counseling and medical care to achieve normal sugar levels prior to attempting pregnancy. Women with uncontrolled diabetes at the time of conception have a fourfold increased risk of birth defects and a higher rate of miscarriage. Achieving normal sugar levels prior to conception can decrease these risks to that similar for nondiabetic women. A diabetic patient should also undergo a complete physical exam to check for other complications associated with diabetes including high blood pressure, kidney disease, and eye disease. Diabetics with high blood pressure, kidney disease or both are at risk for pregnancy complications including preeclampsia (toxemia), poor growth of the baby, and premature delivery.
Pregnant patients may also need to check their blood sugar levels more frequently. Goals for sugar levels are generally stricter during pregnancy than outside pregnancy. Dietary caloric intake is based on prepregnacy weight and height with average diets consisting of 2200-2400 kcal per day, with 50-60% as carbohydrate, 12-20% as protein, and the remainder as fat, divided into three meals and three snacks to avoid major fluctuations of blood sugar levels. Ongoing consultation with a dietitian is essential to maintaining normal blood sugars.
Testing for the well-being of the developing baby includes an ultrasound in the first trimester to establish the due date accurately. Patients are offered blood testing called alpha-fetoproetein screening at 16 to 18 weeks gestation to evaluate for possible spina bifida, which is more common in diabetic pregnancies. An ultrasound and echocardiogram is usually performed at 20 weeks to evaluate for birth defects such as heart and spine abnormalities. Additional ultrasounds are performed during the pregnancy to monitor for growth abnormalities in the baby. During the third trimester testing with non-stress tests and/or biophysical profiles, which are tests that evaluate fetal well-being by evaluating the heart rate and fetal movements, are performed once or twice a week.
Sugar control must also be maintained during labor to prevent complications for both the mother and baby. This is often accomplished by giving sugar and insulin through the IV and monitoring the mother’s blood sugar levels every one to two hours. Maintaining normal sugar level throughout pregnancy and labor has been associated with decreased risks of low blood sugar, jaundice, breathing difficulties, birth defects, premature birth, and birth injury for the baby.
Women without Prepregnancy Diabetes
The American College of Obstetricians and Gynecologists currently recommends that all nondiabetic pregnant women should be screened for gestational diabetes. Generally a patient is screened at 24 to 28 weeks with a one-hour glucose challenge test in which she is given a drink with 50 grams of glucose and her blood is drawn one hour later. If this value is abnormal, then a three hour test is performed in which the women is given a drink with 100 grams of glucose and blood is drawn fasting and at one, two, and three hour intervals. If two or more values are abnormal, then the diagnosis of gestational diabetes is confirmed. Patients with even one abnormal value are at risk of delivering larger babies. However, if a patient has significant risk factors her physician may recommend screening during the first trimester and if the testing is normal, then repeating the testing at 24 to 28 weeks.
Women diagnosed with gestational diabetes can often control their sugars with diet and exercise and should work closely with a dietitian to develop an appropriate diet. Some women will also need oral medications or insulin injections in addition to an appropriate diet. Women with gestational diabetes should monitor their blood sugar levels in similar fashion to pregestational diabetics to evaluate control and the goals for sugar levels are the same as for pregestational diabetics. Normal sugar levels must also be maintained during labor to prevent maternal and fetal complications however; most gestational diabetics will not require insulin during labor. Women with gestational diabetes also tend to have larger babies, which can increase the risk of birth injury, admission of the baby to the special care nursery, and increases the risk of needing a cesarean delivery. Finally, 50% of women with gestational diabetes will develop type II diabetes within 10-15 years after the pregnancy and should be tested for diabetes following the post-partum period and yearly thereafter. The risk of developing type II diabetes can be decreased by dietary and lifestyle modifications.
Provided there is normal fetal growth and testing, both prepregnancy and gestational diabetics can be allowed to labor and have a spontaneous vaginal delivery with a cesarean reserved for usual indications. However, if complications occur, induction of labor or cesarean delivery may be needed prior to the due date. With current standards of care, patients with diabetes should have pregnancy outcomes similar to nondiabetic patients. Education is a vital component to delivering a healthy baby. Integrated care with educators, dietitians, and physicians as well as a properly motivated patient is essential for optimization of pregnancy outcome in women with diabetes.