High Blood Pressure During Pregnancy

Chronic hypertension is high blood pressure that is diagnosed before pregnancy, or before the 20th week of pregnancy. This type of high blood pressure does not go away after delivery. Medical experts do not fully understand what causes chronic hypertension. Genes, diet and lifestyle may play a role.

Hypertension may narrow or tighten the blood vessels in the uterus that supply the baby with oxygen and nutrients. Hypertension during pregnancy can create severe risks for both mother and baby, including:

• Health problems for the mother, such as heart attack and stroke
• Slow fetal growth and low birthweight
• Increased risk of preterm delivery
• Placental abruption (separation of the placenta from the uterine wall during delivery; this can cause heaving bleeding and shock, placing both mother and baby in danger)

The good news is that with proper prenatal care, serious problems associated with chronic hypertension can usually be prevented. In fact, most women with high blood pressure have healthy pregnancies. However, about 1 in 4 develops a dangerous condition called preeclampsia.

What You Can Do Before Pregnancy
If you have hypertension, see your health care provider before trying to get pregnant. He or she can help you get your blood pressure under control before you're pregnant. Your provider can also check to be sure that the drugs you're taking are safe to use during pregnancy. He or she can tell you whether you need to change any of the drugs before becoming pregnant. 

Here are some other things you can do before becoming pregnant:

• Work with your provider to lower your blood pressure.
• If losing weight will help control your blood pressure, use diet and exercise to help meet your weight-loss goals.
• Take your blood pressure medicine as prescribed.
• Quit smoking. Smoking damages blood vessel walls. It is especially dangerous for people with high blood pressure. Smoking also harms your baby.

What You Can Do During Pregnancy
To protect your health and the health of your baby during your pregnancy:

• If you have high blood pressure, tell your health care provider early in your pregnancy.
• Go to all your prenatal care visits.
• If your provider tells you to, check your blood pressure and weight at home.

For More Information
Read the March of Dimes fact sheet High Blood Pressure During Pregnancy. The fact sheet includes information on preeclampsia and HELLP syndrome.

January 2007