What Causes High Blood Pressure During Pregnancy?

Written by Robin Madell | Published on November 19, 2013
Medically Reviewed by George T. Krucik, MD, MBA on November 19, 2013

Problems in Pregnancy

High blood pressure, or hypertension, is defined as blood pressure higher than 140/90 mm Hg. The condition can become a major problem for some pregnant women. Women who have had pre-existing high blood pressure are at higher risk for related complications during pregnancy than those with normal blood pressure.

While having hypertension during pregnancy can often pass uneventfully, it can cause serious health complications for both mother and developing fetus.  According to the CDC, hypertension-related problems during pregnancy are among the leading causes of death for expectant mothers.

Read through to learn more about the condition, and how regular screening and good prenatal care can lower your risk.

Why We Worry: Preeclampsia

While hypertension can be problematic in any case, when you’re pregnant, it carries special risks.

After 20 weeks of pregnancy, high blood pressure can lead to a condition called preeclampsia. Also known as toxemia and pregnancy-induced hypertension, the condition can cause serious damage to your organs, including your brain and kidneys. Preeclampsia with seizures may become eclampsia, which can be fatal.

Thorough prenatal care, including regular doctor’s visits, should be able to spot some of the symptoms of preeclampsia, including protein in a urine sample, abnormal swelling in hands and feet, and persistent headaches.

What to Watch For

During pregnancy, your doctor will monitor your blood pressure during regular check-ups. A reading higher than 140/90 mm Hg will indicate that there’s a problem.

Preeclampsia is harder to diagnose than hypertension. Your doctor will check for signs of protein in your urine along with high blood pressure if preeclampsia is suspected. Your doctor may also want to perform a non-stress test to ensure the fetus is moving and has a normal heart rate. An ultrasound may also be done to check fluid levels and the health of the fetus.

Possible Causes

According to the National Heart, Lung and Blood Institute (NHLBI), there are several possible causes of high blood pressure during pregnancy.

Unhealthy lifestyle choices may lead to high blood pressure during pregnancy. Being overweight or obese, or failing to stay active, are major risk factors for high blood pressure.

The NHLBI emphasizes that it’s important to take preventive measures both before becoming pregnant, and during your pregnancy, to help lessen your risk of high blood pressure. You should steer clear of smoking and drinking alcohol, both of which have been known to raise blood pressure.

Avoiding Preeclampsia

There are a number of risk factors for preeclampsia, including advanced maternal age (over 35), first pregnancy, and carrying multiple fetuses. Other risk factors, such as obesity and a history of high blood pressure, can be minimized with weight loss through diet and exercise..

Those over 40, under 20, or who have certain health conditions including diabetes also have greater risk.

Be sure to talk to your doctor if you fall into a high-risk group.

Understanding Gestational Hypertension

Another type of high blood pressure during pregnancy is called gestational hypertension. Like preeclampsia, gestational hypertension can occur after 20 weeks of pregnancy.

However, gestational hypertension is a relatively mild hypertensive condition, does not compromise a woman’s pregnancy, and tends to disappear after giving birth.

The only potential complication of gestational hypertension is the need to induce labor, resulting in a higher rate of a C-section.

If gestational hypertension is diagnosed before 30 weeks, there’s a higher risk of progressing to preeclampsia.

Medication Concerns

It’s important to understand and avoid the possible causes of hypertension during pregnancy. One reason for this is because it can be problematic to take blood pressure medications while pregnant.

According to the Mayo Clinic, these medications for lowering blood pressure should be avoided when you are pregnant:

  • ACE inhibitors
  • renin inhibitors
  • angiotensin receptor blockers

Talk to your doctor about how to control your blood pressure if you develop hypertension during pregnancy.

Be Informed

According to Stanford Hospital and Clinics, hypertensive disorders resulting from high blood pressure are the second leading cause of U.S. maternal death during pregnancy.

While high blood pressure during pregnancy doesn’t often lead to serious problems, if not treated, hypertension can become life threatening for both mother and fetus.

Take the time to understand the risk factors and possible causes of high blood pressure before you get pregnant—and practice preventive measures to keep your blood pressure down during pregnancy.

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