What are the risks if I have high blood pressure or preeclampsia during pregnancy?

A pregnant woman with severe preeclampsia or severe hypertension is at risk for congestive heart failure, seizures, kidney or liver problems, vision changes, and stroke. Some studies have shown that women over 40 who have had hypertension for 15 or more years are the most likely to have these problems.

All forms of high blood pressure can cause complications during pregnancy and birth. Those include:

  • Low birth weight High blood pressure can cause the blood vessels to constrict and decrease in the uterus, which will affect the supply of oxygen and nutrients to the baby.
  • Placental abruption When the placenta partially or completely peels away from the uterine wall before delivery, it can deprive the baby of oxygen and nutrients and cause heavy bleeding in the mother. Untreated abruption is dangerous for both mother and child.
  • Preterm delivery Some women with severe high blood pressure or preeclampsia require an early delivery to prevent potentially life-threatening complications to the mother and child.

The risk for these complications is highest for women with severe chronic hypertension accompanied by preeclampsia. And having chronic hypertension significantly increases your risk of developing preeclampsia. As many as 1 in 4 women with chronic hypertension and half of women with severe chronic hypertension will develop preeclampsia during pregnancy.

How is high blood pressure monitored and managed during pregnancy?

With close observation and careful management, most women with chronic or gestational hypertension have healthy pregnancies.

At every prenatal appointment, a caregiver will take your blood pressure by wrapping an inflatable cuff around your upper arm. Your urine will be checked for excess protein to determine whether you have preeclampsia.

Ultrasounds and fetal heart rate testing are usually done repeatedly to measure your baby's well-being. Your provider may refer you to a high-risk pregnancy specialist, called a perinatologist.

It's important to go to all of your prenatal appointments because hypertension can get significantly worse during pregnancy and cause serious problems for you and your baby. But also keep in mind that blood pressure often becomes somewhat lower on its own during the second trimester, says Andrea Jackson, an ob-gyn at the Physician & Midwife Collaborative in Alexandria, Virginia. "This is not a sign to lose vigilance, because it typically goes back up in the third trimester," she says.

If you have chronic high blood pressure, it's a good idea to see your healthcare provider before you try to conceive. A preconception appointment allows your provider to ensure that your blood pressure is under control and to evaluate any medication you're taking.

While some medications are considered safe during pregnancy, others – such as ACE inhibitors – should not be taken during pregnancy.

It's important to take prescription medication according to the instructions you're given. Don't stop taking it or adjust the dosage without your caregiver's consent.

If you have mild hypertension, your provider may advise you to stop taking your medication or reduce the dose. If it's severe, you'll probably need to take medication throughout your pregnancy.

If at any time during pregnancy, your blood pressure gets too high, you'll be hospitalized until it's under control.

For more information, see our articles on chronic hypertension and gestational hypertension.