Patient information: Care during pregnancy for women with type 1 or 2 diabetes mellitus

INTRODUCTION

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 tight blood sugar control, which requires frequent daily blood sugar monitoring and 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".)

IMPORTANCE OF BLOOD GLUCOSE CONTROL

Glucose in the mother's blood crosses the placenta and enters the baby's bloodstream to help provide energy for it; thus, high blood sugar levels in the mother leads to high blood sugar levels in the developing baby as well.

High blood sugar levels can cause several problems:

• Early in pregnancy, high sugar levels increase the risk of miscarriage and birth defects. These risks are highest when the 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 sugar levels can cause the infant's size and weight to be larger than normal (see 'Ultrasound' below) and increase the risk of complications during and after delivery (see 'Newborn issues' below.
• In particular, women with large infants are more likely to have difficulty delivering vaginally or require cesarean delivery.

These complications occur less frequently when blood sugar levels are carefully controlled.

General measures to control blood sugar

• Most women with type 1 diabetes will require two to four insulin injections per day. An alternate option is to use an insulin pump.

Women with type 2 diabetes who have been controlled with diet or oral medications may require insulin 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".)

• Frequent contact with health care providers is important for managing blood sugar levels and monitoring the health of the woman and her baby. The healthcare provider may want to review blood sugar levels and insulin doses one or more times per week; this can usually be done via telephone, e-mail, or fax.
• Oral diabetes medications, (eg, glyburide, metformin) have been used to manage gestational or type 2 diabetes in some cases. These medications can control blood sugar levels, but large studies of their safety have not been performed. As a result, the American College of Obstetricians and Gynecologists and American Diabetes Association do not recommended these medications during pregnancy. Women who are taking these drugs when they become pregnant should speak with their healthcare provider.
• A nutritionist can help to plan a diet 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 sugar 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 sugar levels — Frequent sugar monitoring is recommended during pregnancy, including testing before and after each meal. (See "Patient information: Self-blood glucose monitoring in diabetes mellitus".) Target blood sugar levels during pregnancy are slightly lower than those of nonpregnant people.

The American College of Obstetricians and Gynecologists recommends the following goals:

• Fasting: 60 to 90 mg/dL (3.3 to 5 mmol/L)
• Preprandial (before meals): less than 100 mg/dL (5.6 mmol/L)
• One-hour postprandial (after meals): less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L)
• Two-hour postprandial: less than 120 mg/dL (6.7 mmol/L)

A1C is a blood test that represents the average blood sugar 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 sugar of 120 mg/dL [6.7 mmol/L]), (table 1).

Attempting to be at or below 6 percent can cause frequent episodes of low blood sugar, so A1C goals should be determined individually. (See "Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus".)

CARE DURING PREGNANCY

Ideally, a woman with diabetes who is planning pregnancy should consult her health care provider well before she becomes pregnant. This provides an opportunity to make sure blood sugars are in optimal control, adjust medications if needed, evaluate and treat any medical complications related to diabetes, 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. Some of the components of this evaluation are shown in table 2 (table 2).

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. A summary of the testing recommended during pregnancy is shown in the table (table 3).

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 goes down during pregnancy (usually as a result of tight blood sugar control).

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, although 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 (nifedipine, diltiazem), hydralazine, or beta blockers (atenolol, propranolol). Beta blockers can mask some symptoms of low blood sugar 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 during pregnancy, and should be discontinued in any woman planning pregnancy.

High blood pressure complications — Gestational hypertension (high blood pressure during pregnancy) and preeclampsia are more common in women with diabetes. Preeclampsia is a condition that can occur in pregnancy that causes hypertension (blood pressure greater than 140/90) and proteinuria (protein in the urine). Fortunately, most cases are mild. In severe cases (eclampsia), seizure, stroke, heart failure, kidney damage, and rarely, maternal death can occur. (See "Patient information: Preeclampsia".)

Preeclampsia cannot be prevented; if the condition is severe, the only treatment is to deliver. Women with moderately elevated blood pressure may be monitored for days or even weeks if preeclampsia develops before term (36 weeks); this may require the woman to stay in the hospital. Steroids may be given to encourage the fetus's lungs to mature more rapidly. However, steroids significantly increase the woman's blood sugar levels, and usually require a temporary increase in the insulin dose. (See "Patient information: Preeclampsia".)

Kidney function monitoring — Pregnancy does not cause diabetes-related kidney disease (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 other pregnancy complications, such as preeclampsia, preterm delivery, babies who are small for their age (intrauterine growth restriction (IUGR)), and a higher frequency of maternal hospitalization and cesarean delivery (table 4). 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?" and "Patient information: Hemodialysis".)

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 because these infants may be at increased risk for neural tube defects. Some experts recommend a fetal echocardiogram (an ultrasound of the fetus's heart, done through the mother's abdomen); infants of diabetic women who have uncontrolled high sugar levels in early pregnancy have an increased risk of heart defects.

Other testing for birth defects is also recommended. (See 'Screening for birth defects' below.)

To monitor 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".)

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 sugar 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 or position 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 1 out of 4 macrosomic births in women with diabetes (table 5).

Screening for birth defects — Birth defects are more common in infants of women with elevated blood sugar levels before and during the early weeks of pregnancy; most birth defects develops by the 10th week of pregnancy. There is no particular birth defect caused by maternal diabetes. However, studies have shown that tight blood sugar 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.

Screening for birth defects, such as spina bifida and Down syndrome, is recommended to all pregnant women, not just those with diabetes. Women with diabetes are not at increased risk for having a baby with a chromosomal abnormality, such as Down's syndrome, but they are at increased risk of having a baby with a neural tube defect (eg, spina bifida).

Screening may be performed in the first or early second trimester, depending upon the type of screening test. (See "Patient information: First trimester and integrated screening for Down syndrome" and "Patient information: Second trimester screening for Down syndrome".)

Fetal testing — Close monitoring of the fetus is recommended during the third trimester, usually starting at 32 to 38 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 sugar 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 needed to determine if the infant's lungs are ready. (See "Patient information: Amniocentesis".)

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 estimated fetal weight (by ultrasound measurement) is greater than 4500 grams (9 lbs, 14 oz). (See "Patient information: Cesarean delivery".)

Waiting for labor to start on its own is reasonable if blood sugar levels are well-controlled and the mother and fetus 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 carefully controlled diabetes is very low, and is about the same as 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.

INFANT CARE

Newborn issues — The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood sugar 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 sugar 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 sugar 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" and "Patient information: Diabetes mellitus type 2: Overview".)

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 sugar 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 sugar monitoring is important to prevent severe hypoglycemia. (See "Patient information: Deciding to breastfeed" and "Patient information: Breastfeeding basics".)

SUMMARY

• Most women with diabetes can expect an excellent pregnancy outcome as a result of improvements in blood sugar control, as well as obstetrical and neonatal care. This requires close attention to diet, frequent blood sugar testing, and insulin adjustment, as needed.
• Women with diabetes who have elevated blood sugar levels before or during pregnancy are more likely to have complications, including miscarriage, an infant with birth defects, or a large baby that requires cesarean delivery. Pre-existing nephropathy or retinopathy may worsen.
• Frequent visits with a healthcare provider are recommended to monitor blood sugar levels and blood pressure, eye and kidney health, and also to monitor the health of the developing baby.
• Target blood sugar levels during pregnancy are as follows: A!C level: less than 6 (table 1), fasting blood sugar: 60 to 90 mg/dL (3.3 to 5 mmol/L), before meals: less than 100 mg/dL (5.5 mmol/L), one hour after meals: less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L), two-hours after meals: less than 120 mg/dL (6.7 mmol/L).
• 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 poor blood sugar levels, nephropathy, worsening retinopathy, high blood pressure or preeclampsia, or limited or excessive fetal growth. Waiting for labor to start on its own is reasonable if blood sugar levels are well-controlled and the mother and baby do not have problems. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended
• If the baby appears to be very large (based upon ultrasound measurements), cesarean delivery should be considered to avoid possible trauma from shoulder dystocia.
• The infant of the diabetic mother is at risk for several problems in the newborn period. These problems are more common when the mother's blood sugar levels have been elevated during the pregnancy. Most of these problems resolve within a few hours or days of delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems.
• Postpartum (after delivery) care for a woman with diabetes is similar to that for women without diabetes. However, 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 is strongly encouraged, and 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.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Gestational diabetes mellitus
Patient information: Diabetes mellitus type 1: Insulin treatment
Patient information: Self-blood glucose monitoring in diabetes mellitus
Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus
Patient information: Preeclampsia
Patient information: Dialysis or kidney transplantation — which is right for me?
Patient information: Hemodialysis
Patient information: Preterm labor
Patient information: First trimester and integrated screening for Down syndrome
Patient information: Second trimester screening for Down syndrome
Patient information: Amniocentesis
Patient information: Cesarean delivery
Patient information: Diabetes mellitus type 1: Overview
Patient information: Diabetes mellitus type 2: Overview
Patient information: Deciding to breastfeed
Patient information: Breastfeeding basics

Professional Level Information:
Benefits and complications associated with kidney-pancreas transplantation in diabetes mellitus
General principles of insulin therapy in diabetes mellitus
Glycemic control in women with type 1 and type 2 diabetes mellitus during pregnancy
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 gestational diabetes mellitus
Treatment and course of gestational diabetes mellitus

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/diabetesandpregnancy.html, available in Spanish)

• National Institute of Diabetes and Digestive and Kidney Diseases

      (www.diabetes.niddk.nih.gov/dm/pubs/pregnancy/)

• American Diabetes Association (ADA)

      (800)-DIABETES (800-342-2383)
      (www.diabetes.org/gestational-diabetes/pregancy.jsp)

• The Endocrine Society

      (www.endo-society.org)

• The Hormone Foundation

      (www.hormone.org/public/diabetes.cfm, available in Spanish)

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