Before insulin became available in 1922, women with diabetes mellitus were at very high risk of complications of pregnancy. Today, most women with diabetes can have a safe pregnancy and delivery, similar to that of nondiabetic women. This improvement is largely due to good blood glucose (sugar) control, which requires adherence to diet, frequent daily blood glucose monitoring, and frequent insulin adjustment.
This topic review discusses care of women with type 1 or 2 diabetes during pregnancy, as well as fetal and newborn issues. It does not address gestational diabetes, which develops during pregnancy. (See "Patient information: Gestational diabetes mellitus (Beyond the Basics)".)
IMPORTANCE OF BLOOD GLUCOSE CONTROL
Glucose in the mother's blood crosses the placenta to provide energy for the baby; thus, high blood glucose levels in the mother lead to high blood glucose levels in the developing baby as well.
High blood glucose levels can cause several problems:
- Early in pregnancy, high glucose levels increase the risk of miscarriage and birth defects. These risks are highest when hemoglobin A1C is >8 percent or the average blood glucose is >180 mg/dL (10 mmol/L).
- In the last half of pregnancy and near delivery, high blood glucose levels can cause the baby's size and weight to be larger than normal and increase the risk of complications during and after delivery (see 'Newborn issues' below). In particular, women with large babies are more likely to have difficulty having a vaginal birth and have a higher chance of needing a cesarean delivery.
These complications occur less frequently when blood glucose levels are carefully controlled.
General measures to control blood glucose
- Women with type 2 diabetes who have been treated with diet or oral medications generally require insulin for blood glucose control during pregnancy. Oral diabetes medications (eg, glyburide, metformin) have been used to manage type 2 diabetes during pregnancy in some cases. These medications can control blood glucose levels, but multiple large studies of their safety and efficacy have not been performed. For this reason, the American College of Obstetricians and Gynecologists and American Diabetes Association do not recommend using these medications during pregnancy. Women who are taking these medications when they become pregnant should speak with their healthcare provider, and may be switched to insulin therapy.
- Most women with type 1 diabetes will require two to four insulin injections per day. Women who use an insulin pump may continue to do so during pregnancy. Women with diabetes need more insulin during pregnancy, especially during the last one-third of pregnancy (approximately 26 to 40 weeks of pregnancy) because the body becomes resistant to insulin as the pregnancy progresses. (See "Patient information: Diabetes mellitus type 1: Insulin treatment (Beyond the Basics)".)
- Frequent contact with healthcare providers is important for managing blood glucose levels and monitoring the health of the woman and her baby. The healthcare provider may want to review blood glucose levels and insulin doses one or more times per week; this can usually be done via telephone, e-mail, or fax.
- A nutritionist can help to plan a diet for pregnant diabetic women that provides the optimal number of calories, carbohydrate, and snacks/meals throughout the day. The optimal number of calories depends upon the woman's prepregnancy weight and activity level.
- Exercise is an excellent way to control weight and blood glucose levels. Most women who exercised before pregnancy can continue to do so during pregnancy at the same or a slightly reduced pace. Moderate intensity exercise, such as brisk walking, is recommended. Women who did not exercise previously may begin to exercise during pregnancy after consulting with their healthcare provider. Exercise intensity, type, and duration may need to be modified as the pregnancy progresses or if complications develop. (See "Recommendations for exercise during pregnancy and the postpartum period".)
Target blood glucose levels — Frequent blood glucose monitoring is recommended during pregnancy, including testing before and after each meal. (See "Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)".) Target blood glucose levels during pregnancy are slightly lower than those of non-pregnant people.
The American College of Obstetricians and Gynecologists recommends the following goals when self-monitoring blood glucose levels during pregnancy:
- Fasting glucose concentrations ≤95 mg/dL (5.3 mmol/L)
- Preprandial glucose concentrations no higher than 100 mg/dL (5.6 mmol/L)
- One-hour postprandial glucose concentrations no higher than 140 mg/dL (7.8 mmol/L)
- Two-hour postprandial glucose concentrations no higher than 120 mg/dL (6.7 mmol/L)
- Mean capillary glucose 100 mg/dL (5.6 mmol/L)
- During the night, glucose levels should not decrease to less than 60 mg/dL (3.3 mmol/L)
The American Diabetes Association recommends the following glucose goals:
- Preprandial, bedtime, and overnight glucose concentrations 60 to 99 mg/dL (3.3 to 5.5 mmol/L)
- Peak postprandial glucose concentrations 100 to 129 mg/dL (5.6 to 7.2 mmol/L) one to two hours after the beginning of the meal
Hemoglobin A1C is a blood test that represents the average blood glucose level over the previous two to three months. This test is usually done once per month during pregnancy. The goal is for the A1C to be at or near normal (6 percent or an average blood glucose of 120 mg/dL [6.7 mmol/L]) (table 1). However, attempting to be at or below 6 percent can cause frequent episodes of low blood glucose, so target A1C goals should be determined individually. (See "Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)".)
CARE DURING PREGNANCY
Ideally, a woman with diabetes who is planning pregnancy should consult her healthcare provider well before she becomes pregnant. This provides an opportunity to make sure blood glucose levels are in optimal control, adjust medications if needed, evaluate and treat any medical complications related to diabetes (such as diabetes-related eye disease), and start folic acid supplementation (at least 400 mcg per day is recommended, starting at least one month before conception). It is also an opportunity to discuss how pregnancy may affect diabetes and vice versa.
Care during pregnancy is a team effort involving an obstetrician and an endocrinologist or internist who oversees insulin management and medical care. Some family practitioners perform all of these functions.
Eye examination — Retinopathy refers to abnormal, leaky blood vessels in the light sensitive tissue lining the back of the eye (the retina). Retinopathy can lead to vision problems, and even blindness in severe cases. Pregnancy can worsen diabetic retinopathy. The risk of worsening retinopathy during pregnancy is increased in those with the highest initial A1C values and in women whose A1C falls rapidly during pregnancy.
The impact of pregnancy on diabetic retinopathy is mild and temporary for most women; the retina usually returns to its prepregnancy condition within several months after delivery. Nevertheless, all women with type 1 or 2 diabetes should have an eye examination by an ophthalmologist or optometrist before pregnancy and during the first trimester (three months). In most cases, a follow-up examination is recommended every three months until delivery, depending upon the results of the initial examination.
Women with severe retinopathy are more likely to experience progression and complications. Eye examinations before and during pregnancy, along with close monitoring and treatment (as needed) of retinopathy can minimize the risk of vision loss. Some experts have recommended cesarean delivery for women with retinopathy, but this is controversial; most women can attempt a vaginal delivery.
Blood pressure monitoring — Blood pressure may become elevated during pregnancy and should be measured at every appointment. High blood pressure often improves during the first half of pregnancy, but returns to baseline or worsens in the second half.
Medications to treat high blood pressure during pregnancy may include methyldopa, calcium channel blocking agents, hydralazine, or beta blockers. Beta blockers can mask some symptoms of low blood glucose and should be used with caution.
Angiotensin converting enzyme (ACE) inhibitors (captopril, lisinopril, enalapril) and angiotensin II receptor blockers (ARBs, losartan, valsartan) are not safe for the fetus, and should be discontinued in any woman planning pregnancy.
High blood pressure complications — Gestational hypertension (high blood pressure during pregnancy) and preeclampsia (high blood pressure and protein in the urine during pregnancy) are more common in women with diabetes. Fortunately, most cases are mild. In severe cases, seizure, stroke, heart failure, kidney damage, and rarely, maternal death can occur. (See "Patient information: Preeclampsia (Beyond the Basics)".)
Kidney function monitoring — Pregnancy does not cause diabetes-related kidney disease (called diabetic nephropathy), but it can worsen existing disease. Kidney function is monitored during pregnancy by urine dipstick testing for protein, which is usually performed at every prenatal visit. Other urine or blood tests may be ordered depending upon the individual's situation.
Diabetic nephropathy may increase the risk of developing other pregnancy complications, such as preeclampsia, preterm delivery, and babies who are small for their age (intrauterine growth restriction). Women with these complications have a higher frequency of hospitalization during pregnancy and cesarean delivery. Women with retinopathy and kidney disease are at increased risk of having a small infant because blood flow to the placenta may be reduced.
If a woman develops worsening nephropathy during pregnancy, it is usually temporary and reverts to the prepregnancy condition within several months of delivery. Nephropathy probably worsens because blood flow through the kidney increases by 50 percent during pregnancy, which increases the kidneys' workload. In addition, some women develop high blood pressure or new pregnancy-induced high blood pressure, which further stresses the kidney.
Permanent kidney damage, including kidney failure, can occur in women who already have significant nephropathy before becoming pregnant. These women may require dialysis or kidney transplant sooner than a woman with severe chronic kidney disease who never becomes pregnant. (See "Patient information: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)" and "Patient information: Hemodialysis (Beyond the Basics)".)
Ultrasound — Ultrasound may be recommended for several reasons during pregnancy.
To determine the due date — An ultrasound examination of the baby is recommended during the first trimester of pregnancy (before 13 weeks) if there is any uncertainty about the date of the last menstrual period. It is important that the due date is accurate because decisions about when to begin fetal testing and when to deliver the baby are based upon this date.
To screen for birth defects — Ultrasound examination is recommended at 18 to 20 weeks gestation to screen for birth defects. The examination should pay particular attention to the spine and heart because infants of diabetic mothers may be at increased risk for neural tube defects and heart defects.
To monitor amniotic fluid levels — Ultrasound is also used to monitor the amount of amniotic fluid around the fetus; polyhydramnios is an abnormal increase in the amount of amniotic fluid. Polyhydramnios is more common in women with diabetes than in women without diabetes. Polyhydramnios related to diabetes is usually mild and does not cause problems. If the fluid levels become severely elevated, maternal discomfort, uterine contractions, premature rupture of the membranes ("breaking the water"), and preterm delivery can occur. (See "Patient information: Preterm labor (Beyond the Basics)".)
To monitor the baby's growth — Ultrasound is also used to monitor the baby's growth and development throughout the pregnancy, although ultrasound estimates of the baby's weight can be off by as much as 15 percent. Macrosomia is a condition in which an infant weighs more than nine pounds (4000 grams) at term (≥37 weeks of pregnancy), and is more common in women with diabetes. High fetal insulin levels, which can develop in response to elevated maternal blood glucose levels, are one potential cause of macrosomia since insulin stimulates fetal growth.
Macrosomia occurs in 15 to 45 percent of diabetic pregnancies. Cesarean delivery may be needed if labor does not progress normally because of the large size of the baby. In addition, macrosomic infants are at higher risk of being injured during delivery and may be delivered by cesarean delivery before labor if there is a concern that the infant's shoulders may be difficult to deliver through a woman's pelvis (called shoulder dystocia). Shoulder dystocia occurs in one out of four macrosomic births in women with diabetes.
Screening for birth defects — Birth defects are more common in infants of women with high blood glucose levels before and during the early weeks of pregnancy; most birth defects develop by the 10th week of pregnancy. There is no particular birth defect caused by maternal diabetes; neural tube defects and heart defects are the most common birth defects. However, studies have shown that very good blood glucose control before becoming pregnant reduces the risk of birth defects to a level that is similar to that of women who do not have diabetes. In addition, to reduce the risk of neural tube defects, women planning pregnancy should begin taking folic acid supplements in a multivitamin or prenatal vitamin one to two months prior to attempting to conceive and continue supplementation at least through the first trimester.
Women with diabetes do not have a higher risk of having a baby with a chromosomal abnormality, such as Down syndrome, than women without diabetes. The risk of having a baby with Down syndrome primarily depends on the mother’s age and whether there is a family history of Down syndrome. (See "Patient information: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)".)
Fetal testing — Close monitoring of the fetus is recommended during the third trimester, usually starting at 32 weeks of pregnancy. This usually includes weekly to twice-weekly nonstress testing. This is done by monitoring the baby's heart rate with a small device that is placed on the mother's abdomen. The device uses sound waves (ultrasound) to measure the baby's heart rate over time, usually for 20 to 30 minutes.
Normally, the baby's baseline heart rate should be between 110 and 160 beats per minute and should increase above its baseline by at least 15 beats per minute for 15 seconds when the baby moves.
The test is considered reassuring (called "reactive") if two or more fetal heart rate increases are seen within a 20 minute period. Further testing may be needed if these increases are not seen after monitoring for 40 minutes.
PLANNING FOR DELIVERY
A woman and her obstetrician may decide to schedule the date of her delivery (either an induction of labor or cesarean delivery), especially if there are risk factors, such as increased blood glucose levels, nephropathy, worsening retinopathy, high blood pressure or preeclampsia, or if the baby is smaller or larger than normal. If delivery before the due date is planned, an amniocentesis may be recommended to determine if the baby’s lungs are ready for breathing. (See "Patient information: Amniocentesis (Beyond the Basics)".)
If the fetus appears to be very large (based upon ultrasound measurements), a woman and her obstetrician may consider cesarean delivery to avoid possible trauma from shoulder dystocia. The American College of Obstetricians and Gynecologists suggests that a woman and her physician consider a planned cesarean delivery if the baby’s estimated weight (by ultrasound measurement) is greater than 4500 grams (9 lbs, 14 oz). (See "Patient information: C-section (cesarean delivery) (Beyond the Basics)".)
Waiting for labor to start on its own is reasonable if blood glucose levels are well-controlled and the mother and baby are doing well. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended; some practitioners routinely induce labor between 39 and 40 weeks in all women with type 1 or 2 diabetes.
The risk of stillbirth for pregnant women with well-controlled diabetes is very low, and is about the same as in women without diabetes (less than 1 percent). The mortality (death) rate in infants of diabetic women is slightly higher than in nondiabetics (2 versus 1 percent). This is mostly due to a higher rate of serious birth defects in infants of diabetic mothers.
Newborn issues — The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels, jaundice, breathing problems, excessive red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been high throughout the pregnancy. Most of these problems resolve within a few hours or days after delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems.
Infants of mothers with diabetes are at higher risk of having difficulties with breathing, especially if the infant is born earlier than 39 weeks. This is because the lungs appear to develop more slowly in infants of women with diabetes. The risk of breathing problems is highest when maternal blood glucose levels have been high near the time of delivery.
Will my child develop diabetes? — The children of parents with diabetes are at increased risk of developing the same type of diabetes. According to the American Diabetes Association:
- Children of a father with type 1 diabetes have a 1 in 17 risk of developing type 1 diabetes. Children of a mother with type 1 diabetes have a 1 in 25 risk if, at the time of pregnancy, the mother is less than 25 years of age. The risk is 1 in 100 risk if the mother is 25 years of age or older. These risks are doubled if the affected parent developed diabetes before age 11. If both parents have type 1 diabetes, the child's risk is 1 in 4 to 10 (10 to 25 percent risk).
- The risk of diabetes in children of a parent with type 2 diabetes is 1 in 7 if the parent was diagnosed before age 50 and 1 in 13 if the parent was diagnosed after age 50. The child's risk may be greater when the parent with type 2 diabetes is the mother. If both parents have type 2 diabetes, the risk to the child is about 1 in 2. (See "Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)" and "Patient information: Diabetes mellitus type 2: Overview (Beyond the Basics)".)
AFTER DELIVERY CARE
Postpartum (after delivery) care of a woman with diabetes is similar to that of women without diabetes. However, it is important to pay close attention to blood glucose levels because insulin requirements change significantly in the first few days after delivery; some women require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours.
Breastfeeding — In all women (with and without diabetes), breastfeeding is strongly encouraged because it benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. (See "Patient information: Deciding to breastfeed (Beyond the Basics)" and "Patient information: Breastfeeding guide (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Care during pregnancy for women with type 1 or type 2 diabetes (The Basics)
Patient information: How to plan and prepare for a healthy pregnancy (The Basics)
Patient information: Preparing for pregnancy when you have diabetes (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Gestational diabetes mellitus (Beyond the Basics)
Patient information: Diabetes mellitus type 1: Insulin treatment (Beyond the Basics)
Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)
Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)
Patient information: Preeclampsia (Beyond the Basics)
Patient information: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)
Patient information: Hemodialysis (Beyond the Basics)
Patient information: Preterm labor (Beyond the Basics)
Patient information: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)
Patient information: Amniocentesis (Beyond the Basics)
Patient information: C-section (cesarean delivery) (Beyond the Basics)
Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)
Patient information: Diabetes mellitus type 2: Overview (Beyond the Basics)
Patient information: Deciding to breastfeed (Beyond the Basics)
Patient information: Breastfeeding guide (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Benefits and complications associated with kidney-pancreas transplantation in diabetes mellitus
General principles of insulin therapy in diabetes mellitus
Medical management of type 1 and type 2 diabetes mellitus in pregnant women
Infant of a diabetic mother
Nutrition in pregnancy
Obstetrical management of pregnancy complicated by pregestational diabetes mellitus
Pregnancy in women with diabetic nephropathy
Prepregnancy evaluation and management of women with type 1 or type 2 diabetes mellitus
Recommendations for exercise during pregnancy and the postpartum period
Screening and diagnosis of diabetes mellitus during pregnancy
Medical management and follow-up of gestational diabetes mellitus
The following organizations also provide reliable health information.
- National Library of Medicine
(www.nlm.nih.gov/medlineplus/diabetesandpregnancy.html, available in Spanish)
- National Institute of Diabetes and Digestive and Kidney Diseases
- American Diabetes Association (ADA)
(www.hormone.org/public/diabetes.cfm, available in Spanish)