Mayo Clinic Health Library

High blood pressure and pregnancy: Know the facts

Updated: 07-30-2011

High blood pressure (hypertension) during pregnancy — whether you develop the condition before or after conception — requires special care. Here's what you need to know about high blood pressure and pregnancy.

Why is high blood pressure a problem during pregnancy?

High blood pressure during pregnancy poses various risks, including:

  • Decreased blood flow to the placenta. This reduces the baby's supply of oxygen and nutrients, potentially slowing the baby's growth and increasing the risk of a low birth weight.
  • Placental abruption. With this condition, the placenta prematurely separates from the uterus. Placental abruption can deprive the baby of oxygen and cause heavy bleeding in the mother.
  • Premature delivery. Sometimes an early delivery is needed to prevent potentially life-threatening complications.
  • Future cardiovascular disease. Women who develop preeclampsia — a serious condition characterized by high blood pressure and protein in the urine after 20 weeks of pregnancy — might be at increased risk of cardiovascular disease later in life, despite the fact that their blood pressure returns to normal after delivery.

Are there different types of high blood pressure during pregnancy?

Sometimes high blood pressure is present before pregnancy. In other cases, high blood pressure develops during pregnancy. For example:

  • Chronic hypertension. If high blood pressure develops before pregnancy, during pregnancy but before 20 weeks or lasts more than 12 weeks after delivery, it's known as chronic hypertension.
  • Gestational hypertension. If high blood pressure develops after 20 weeks of pregnancy, it's known as gestational hypertension. Gestational hypertension usually goes away after delivery.
  • Preeclampsia. Sometimes chronic hypertension or gestational hypertension leads to preeclampsia, a serious condition characterized by high blood pressure and protein in the urine after 20 weeks of pregnancy. Left untreated, preeclampsia can lead to serious — even fatal — complications for mother and baby.

What do I need to know about preeclampsia?

Warning signs of preeclampsia — which can develop gradually or strike suddenly, often in the last few weeks of pregnancy — may include:

  • Persistent headaches
  • Changes in vision, including blurred vision, flashing lights, sensitivity to light and vision loss
  • Upper abdominal pain, usually on the right side
  • Sudden weight gain, typically more than 5 pounds (2.3 kilograms) a week

Swelling (edema), particularly in the face and hands, often accompanies preeclampsia as well. Swelling isn't considered a reliable sign of preeclampsia, however, because it also occurs in many normal pregnancies.

If you develop signs of preeclampsia, you and your baby will be closely monitored. Sometimes bed rest or hospitalization is recommended. The only cure for preeclampsia is delivery of the baby.

Is it safe to take blood pressure medication during pregnancy?

Any medication you take during pregnancy can affect your baby. Although some medications used to lower blood pressure are considered safe during pregnancy, others — such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and renin inhibitors — are generally avoided during pregnancy.

Treatment is important, however. The risk of heart attack, stroke and other problems associated with high blood pressure doesn't go away during pregnancy. And high blood pressure can be dangerous for your baby, too. If you need medication to control your blood pressure during pregnancy, your health care provider will prescribe the safest medication at the most appropriate dose. Take the medication exactly as prescribed. Don't stop taking the medication or adjust the dose on your own.

What should I do to prepare for pregnancy?

If you have high blood pressure, schedule a preconception appointment with the health care provider who'll be handling your pregnancy. Also meet with other members of your health care team, such as your family doctor or cardiologist. They'll evaluate how well you're managing your high blood pressure and consider any treatment changes you might need to make before pregnancy begins. If you're overweight, your health care provider might recommend losing the excess pounds before you try to conceive.

What can I expect during prenatal visits?

During pregnancy, you'll see your health care provider often. Your weight and blood pressure will be checked at every visit, and you might need frequent blood and urine tests.

Your health care provider will closely monitor your baby's health as well. Frequent ultrasounds might be used to track your baby's growth and development. Fetal heart rate monitoring might be used to evaluate your baby's well-being. Your health care provider might also recommend monitoring your baby's daily movements.

What can I do to prevent complications?

Taking good care of yourself is the best way to take care of your baby. For example:

  • Keep your prenatal appointments. Visit your health care provider regularly throughout your pregnancy.
  • Take your blood pressure medication as prescribed. Your health care provider will prescribe the safest medication at the most appropriate dose.
  • Stay active. Follow your health care provider's recommendations for physical activity. Keep in mind, however, that bed rest might be recommended if you develop signs of preeclampsia.
  • Eat a healthy diet. Limit the amount of sodium in your diet, and take your prenatal vitamins.
  • Monitor your weight. Gaining a healthy amount of weight — often 25 to 35 pounds (about 11 to 16 kilograms) — supports your baby's growth and development. There's no one-size-fits-all approach to pregnancy weight gain, though. Work with your health care provider to determine what's right for you.
  • Know what's off-limits. Avoid smoking, alcohol and illicit drugs. Talk to your health care provider before taking any over-the-counter medications.

If you had high blood pressure before you got pregnant, have a history of preeclampsia, are obese, are pregnant with more than one baby, are younger than 20 or older than 40, or have other conditions, such as diabetes, you're at increased risk of preeclampsia. Your health care provider might prescribe low-dose aspirin therapy during your pregnancy to reduce your risk of developing the condition.

What about labor and delivery?

Your health care provider might suggest inducing labor a few days before your due date to avoid complications. If you develop preeclampsia or other complications, induction might be needed even earlier. If you have severe preeclampsia, you might be given medication during labor to help prevent seizures. In some cases, a C-section might be needed.

Will I be able to breast-feed my baby?

Breast-feeding is encouraged for most women who have high blood pressure, even those who take medication. Discuss any medication adjustments you'll need to make with your health care provider ahead of time. Sometimes an alternate blood pressure medication is recommended. Your health care provider might also recommend avoiding breast-feeding right after you take your medication.