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Early Detection: Gestational Diabetes & Preeclampsia

Chances are you'll sail through pregnancy without trouble. But even if you're feeling great, you should still seek regular prenatal care because some health problems that could hurt your baby are symptomless. These include gestational diabetes, which raises blood sugar levels during pregnancy, and preeclampsia, a form of high blood pressure. But with early detection and treatment, you can manage these problems and still have a healthy baby.

What Is It?

Gestational diabetes occurs when pregnancy hormones interfere with the body's ability to use insulin, the hormone that turns blood sugar into energy, resulting in high blood sugar levels. Each year, up to 4 percent of women develop this serious illness in pregnancy.

While most women with gestational diabetes have no symptoms, a small number may experience extreme hunger, thirst, or fatigue.

How Do I Know If I Have It?

Your doctor will probably screen you for gestational diabetes between your 24th and 28th weeks of pregnancy. If you have certain risk factors (see "Who's at Risk?" below), your doctor may opt to screen you sooner. During your screening, you'll drink a sugary liquid, then take a blood test. If your blood sugar levels appear high, you'll need to take a longer test, during which you'll drink more liquid and your blood sugar will be tested several times to determine whether you have gestational diabetes.

What Are the Risks Associated with It?

Women who fail to seek treatment for gestational diabetes run the risk of giving birth to big babies (9 pounds or more), since much of the extra sugar in the mother's blood ends up going to the fetus. Larger babies are more likely to suffer birth injuries during vaginal delivery, as they're more apt to get stuck in the birth canal. Because of this, large babies are often delivered by c-section, and they have an increased risk of developing breathing difficulties and jaundice as newborns.

How Can It Be Treated?

Many women who develop this condition can control their blood sugar levels with diet and exercise. Your doctor or dietitian may design an individualized diet that takes into account your weight, stage of pregnancy, and food preferences. Of this diet, 10 to 20 percent of your calories should come from protein, 30 percent from fats, and the remainder from complex carbohydrates such as whole-grain breads or cereals. If you've been on the diet for two weeks and your blood sugar level hasn't returned to normal, you may need to take insulin shots for the rest of your pregnancy.

Studies have found that women who develop gestational diabetes may also be at risk of developing preeclampsia, though the reason is still unknown.

You may be more likely to develop gestational diabetes if:

  • You are over 30 years of age.
  • You are obese.
  • You have a family history of diabetes.
  • You have had gestational diabetes in a previous pregnancy (you have a 35 to 50 percent chance of developing it again).
  • You previously gave birth to a baby who weighed more than 9 1/2 pounds.
  • You have experienced a stillbirth.
  • You are of African-American, Hispanic/Latino, Pacific Island, South or Eastern Asian, or Native American ancestry.

Preexisting Diabetes

One in 100 women develop diabetes before pregnancy. Unfortunately, women with poorly controlled preexisting diabetes are three to four times more likely than nondiabetic women to have babies with birth defects of the heart or neural tube. Women with preexisting diabetes also have an increased risk of miscarriage and stillbirth. Fortunately, you can significantly reduce these risks by controlling your blood sugar before pregnancy. If you have preexisting diabetes, speak with your doctor before you attempt to conceive.

What Is It?

This potentially serious disorder is characterized by high blood pressure and protein in the urine. It may also be accompanied by swelling of the hands and face, sudden weight gain (5 or more pounds in one week), blurred vision, and stomach pain. You should contact your doctor if you develop any of these symptoms. Preeclampsia affects about 5 percent of pregnant women, most of whom are having their first baby. Unfortunately, preeclampsia's cause remains unknown.

How Do I Know If I Have It?

If you have mild preeclampsia, you may not have any obvious symptoms, so you're unlikely to suspect that something is wrong. That's one reason it's so important to keep all your prenatal appointments. At each visit your healthcare provider will measure your blood pressure and evaluate your urine for protein to check for preeclampsia, so it can be diagnosed and treated quickly.

What Are the Risks Associated with It?

If left untreated, preeclampsia can cause severe problems for you and your baby. This condition may slow your baby's growth and increase your risk of preterm delivery and placental abruption, the separation of the placenta from the uterine wall before delivery.

How Can It Be Treated?

Your healthcare provider can proceed with treatment for preeclampsia, depending upon its severity and how far along you are in pregnancy. If you develop severe preeclampsia after 34 weeks of pregnancy, your doctor may opt to induce labor or, if your case is mild, you can simply reduce your activities. In this situation, you will also need to see your healthcare provider frequently to evaluate your baby's well-being with tests such as ultrasound and fetal heart rate monitoring.

However, women who develop severe preeclampsia before 34 weeks may require hospitalization. This will allow the baby extra time to mature, reducing the risk of serious health complications from prematurity.

If you develop mild preeclampsia after your 37th week of pregnancy, and your cervix has begun to dilate (a sign that it's ready for delivery), your healthcare provider may recommend inducing labor. Inductions are often able to head off potential complications.

You may be more susceptible to preeclampsia if you have any of the following risk factors:

  • This is your first pregnancy.
  • You have a family history of preeclampsia.
  • You had preeclampsia in a previous pregnancy (about 20 percent of women who developed preeclampsia after the 37th week of pregnancy, and up to 65 percent of those who developed it before the 29th week, develop it again).
  • You have a personal history of high blood pressure, kidney disease, or certain thrombophilias (blood-clotting disorders).
  • You are carrying multiples (twins or more).
  • You are younger than 20 years, or over 35 years.
  • You are African-American.
  • You are overweight.

The Mystery of Preeclampsia

Unfortunately, the cause of preeclampsia is unknown, and there is no way to prevent it. However, a recent British study suggests that taking vitamins C and E throughout the second half of pregnancy may help. According to the research, high-risk women who took the vitamins reduced their chances of getting preeclampsia by about 75 percent. More studies are under way to see if this treatment is truly effective.

To receive more information on this topic and many others, visit the Pregnancy & Newborn Health Education Center at the March of Dimes at marchofdimes.com.

Dr. Schwarz, obstetrical consultant to the March of Dimes, is past president of the American College of Obstetricians and Gynecologists. He is also the Vice Chairman for Clinical Services, Department of Obstetrics and Gynecology, Maimonides Medical Center and Emeritus Distinguished Service Professor of Obstetrics and Gynecology, SUNY Downstate Medical Center, both in Brooklyn.

Originally published in American Baby magazine, November 2005. Updated 2010

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.