High blood pressure and pregnancy: Know the facts

High blood pressure and pregnancy isn't necessarily a dangerous combination. Here's what you need to know to take care of yourself — and your baby. By Mayo Clinic Staff

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.

Jul. 30, 2011 See more In-depth