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Hypertension (High Blood Pressure) During Pregnancy


Blood pressure is the force of your blood against the walls of your arteries. High blood pressure is when the force against the arteries is too high. High blood pressure, or hypertension, can be a serious problem for anyone if left untreated. In pregnancy, hypertension can lead to life-threatening complications.

Between 8% and 16% of all pregnant women experience high blood pressure during their pregnancy. Hypertension in pregnancy can occur up to 6 weeks after delivery. The condition can negatively impact both a mother’s and her baby’s health during and after pregnancy, putting the mother at risk for a range of complications, including heart disease, seizures, and coma, and the baby at risk for premature birth and even death.

The good news is that hypertension during pregnancy can be managed with blood pressure medication and other treatments. However, for more serious related conditions, such as preeclampsia/eclampsia, women may need to be hospitalized or closely monitored by their doctors.

What is high blood pressure during pregnancy?

Hypertension in pregnancy is diagnosed when a pregnant person has a blood pressure reading that is 140/90 or higher on two different occasions. Readings of 140/90 or higher are considered mild high blood pressure; those over 160/110 are considered severe high blood pressure.

Blood pressure is measured using an inflatable cuff that tightens around the upper arm. It is recorded as two numbers: the top number (systolic blood pressure) represents the pressure in your blood vessels when your heart beats. The bottom number (diastolic blood pressure) represents the pressure in your blood vessels when your heart relaxes between beats. Everyone’s blood pressure changes throughout the day depending on a variety of factors, such as exercise, eating, caffeine, smoking, and stress. Normal blood pressure readings are 120/80 or lower.

Are there different types of hypertension during pregnancy?

There are several different types of hypertension that occur during pregnancy. If left untreated, some types may lead to more serious complications. These conditions include:

  • Chronic hypertension, which is simply another name for high blood pressure that was present before a person became pregnant or if the condition developed in the first half of her pregnancy (before 20 weeks).
  • Gestational hypertension, when a pregnant person develops high blood pressure during the second half of her pregnancy (after 20 weeks).
  • Preeclampsia, when high blood pressure develops after 20 weeks of pregnancy. One common sign of preeclampsia is a finding of protein in the mother’s urine. Preeclampsia puts stress on the heart and other organs and can cause serious complications, such as restricting the blood supply to the placenta, damaging the liver and kidneys, or causing fluid to accumulate in the lungs. The presence of protein in urine is a sign of kidney dysfunction. Preeclampsia can be mild or severe, but even mild preeclampsia can quickly progress to more severe complications. Preeclampsia often requires early delivery.
  • Eclampsia, a rare but serious, life-threatening complication of preeclampsia that occurs when a pregnant woman has seizures because of untreated or undertreated preeclampsia; this requires emergency medical attention.
  • HELLP syndrome (preeclampsia with Hemolysis, Elevated Liver enzyme levels, and Low Platelet levels), a very rare type of preeclampsia. This is a serious condition that causes liver damage and destroys red blood cells and platelets (blood cells that aid in clotting). Most women with HELLP syndrome will need to deliver their baby earlier than expected.

Eclampsia and HELLP syndrome are both medical emergencies. Preeclampsia can also be a medical emergency, depending on how severe it is. They may be life-threatening to a pregnant woman and her baby if they aren’t treated immediately.

It’s important to note that because chronic or gestational hypertension can develop into preeclampsia/eclampsia, a pregnant woman’s blood pressure will be monitored at every prenatal appointment and her urine will be checked often for protein.

What complications are associated with high blood pressure during pregnancy?

A woman with hypertension during pregnancy is at greater risk of:

  • Placental abruption (when the placenta prematurely separates from the uterine wall)
  • Delivering prematurely (before 37 weeks)
  • Having a Cesarean section
  • Having a low-birthweight baby
  • Having her baby admitted to the neonatal intensive care unit
  • Having a stillborn baby (fetal death)
  • Having her baby die within the first week of life
  • Having a stroke
  • Developing heart disease shortly after delivering the baby
  • Developing heart disease, diabetes, or high cholesterol levels later in life

In most cases, delivering a baby will improve symptoms of preeclampsia/eclampsia and HELLP syndrome. However, some women experience complications of preeclampsia/eclampsia in the days after delivering a baby, or they may even develop the condition up to 6 weeks after childbirth.

What causes hypertension during pregnancy?

Certain risk factors increase the likelihood that a woman will develop high blood pressure during pregnancy, including:

  • Obesity
  • Diabetes
  • Chronic hypertension prior to pregnancy
  • Certain pre-existing medical conditions, like autoimmune diseases
  • Advanced age (35 or older)
  • Being pregnant for the first time
  • Multiple gestation (twins or more)
  • High cholesterol levels
  • A personal or family history of high blood pressure during pregnancy

Doctors don’t yet know why some pregnant women develop preeclampsia/eclampsia or HELLP syndrome.

How can you lower your risk of preeclampsia before pregnancy?

If you have one of the conditions listed above, you may be at higher risk for developing preeclampsia. There are some things you can do before pregnancy to lower your chance of preeclampsia.

A pre-conception visit with an experienced medical team is an opportunity to understand how to best manage existing conditions and risks during pregnancy. Your provider will make sure your medications are safe for pregnancy. They can review your blood pressure to make sure you determine a healthy goal before pregnancy. If you’re overweight, they may recommend losing weight and regular exercise before pregnancy.

What are the symptoms of high blood pressure during pregnancy?

Many pregnant people with high blood pressure don’t experience symptoms. However, some warning symptoms can be present with preeclampsia:

  • Painful headaches
  • Swollen feet, ankles, and legs
  • Swollen face or hands
  • Blurred vision
  • Temporary blindness
  • Light sensitivity
  • Pain in the upper right part of the abdomen, under the ribcage
  • Blood in the urine
  • Severe stomach pain
  • Trouble breathing, typically caused by fluid in the lungs

Pregnant women with preeclampsia or eclampsia may experience:

  • Seizures
  • Stroke
  • Coma

Pregnant women with HELLP syndrome may experience:

  • A feeling of malaise or of being unwell
  • Pain in the upper right part of the abdomen, under the ribcage (from swelling of the liver or bleeding in the liver)
  • Vomiting

How is high blood pressure during pregnancy diagnosed?

A pregnant woman is diagnosed with hypertension if her blood pressure readings are higher than 140 systolic or 90 diastolic on two separate occasions, typically during her visit with her Ob/Gyn provider. If the reading is 160/110 or higher, the woman is diagnosed with severe high blood pressure.

Your medical history is important. Let your doctor know, for instance, if you had high blood pressure before becoming pregnant or if you or a family member was diagnosed with high blood pressure, preeclampsia/eclampsia, or HELLP syndrome during a previous pregnancy.

If you are diagnosed with high blood pressure during pregnancy, you will be offered tests to check for preeclampsia/eclampsia or HELLP syndrome. Tests may include:

  • Blood tests, which may show that the liver or kidneys are not functioning normally, a sign of preeclampsia or HELLP syndrome. Tests can also show that red blood cells have burst (hemolysis) and have leaked hemoglobin (which gives blood its red color) into the blood, a sign of HELLP syndrome. These tests may need to be checked frequently.
  • A urine test, which looks for protein in the urine. High levels of protein can indicate preeclampsia, although not all pregnant people with preeclampsia will have protein in their urine.

How is high blood pressure during pregnancy treated?

Low-dose aspirin (81 mg) is recommended for pregnant people at higher risk for preeclampsia. This is usually started at 12-14 weeks and continued until the last month of pregnancy.

Pregnant women with mild gestational or chronic hypertension may not be treated with medication; instead, doctors may monitor their blood pressure and urine to ensure the condition doesn’t advance to severe hypertension, preeclampsia/eclampsia, or HELLP syndrome.

In some cases, pregnant women with chronic hypertension who took blood pressure medications before becoming pregnant may continue to take them during their pregnancy. However, certain drugs, including ACE inhibitors and ARBs, are unsafe during pregnancy.

Instead, doctors may prescribe blood pressure medications that are safe for pregnancy. Some examples are labetalol, nifedipine, hydralazine, and thiazide diuretics. Treatment of chronic hypertension in pregnancy is important and may prevent preeclampsia.

For women with preeclampsia, delivering the baby when the fetus is mature (between 34 and 37 weeks) is the most common and effective way to improve symptoms. For many women, preeclampsia disappears within 6 weeks after delivery.

Doctors may monitor a pregnant woman with preeclampsia at home or admit her to the hospital for evaluation and treatment that may include:

  • Monitoring her blood pressure and urine frequently
  • Monitoring her liver health and platelet counts to see if HELLP syndrome has developed
  • Monitoring the fetus’s growth
  • Prescribing blood-pressure medication, which may be delivered intravenously or by mouth in the hospital
  • Prescribing anti-seizure medication (magnesium sulfate), which may prevent or treat eclampsia
  • Giving steroid injections to help a baby’s lungs develop more quickly, since early delivery may become necessary

For women with HELLP syndrome, the treatment may include taking medications to reduce blood pressure. In certain cases, a blood transfusion may be necessary. Ultimately, however, the only way to manage HELLP is to deliver the baby, which may be earlier than expected. Most women experience symptom improvement within three days of giving birth.

Call your health care provider immediately if any of the following occurs:

  • Severe headache that will not go away
  • Vision changes (spots, blurring, halos)
  • Sudden swelling of hands and face
  • Pain the right, upper abdomen
  • Sudden weight gain (more than 5 pounds in 1 week)
  • Blood pressure higher than 140 systolic or 90 diastolic

What is the outlook for people with hypertension during pregnancy?

It is possible for women with high blood pressure to have a safe pregnancy if they’re closely monitored and treated.

High blood pressure during pregnancy increases a woman’s risk of short- and long-term complications, including heart disease and diabetes.

Preeclampsia/eclampsia increases the risk of seizures or coma. Preeclampsia/eclampsia that develops after delivery may be life-threatening if it isn’t treated immediately, highlighting the need for frequent monitoring and check-ups with the doctor to ensure a healthy pregnancy for both mother and baby.

What makes Yale unique in treating high blood pressure in pregnant women?

“At Yale Medicine, we focus on providing safe and compassionate care for pregnant mothers affected by hypertension and their families,” says Annalies Denoble, MD, an obstetrician-gynecologist who specializes in maternal-fetal medicine, or high-risk pregnancies. “We understand that complications like high blood pressure in pregnancy can be scary and unexpected. Yale Medicine offers a team-based approach that includes obstetric and cardiology specialists, midwives, lactation specialists, nurses, and pharmacists.”

The Yale Medicine team works together to provide comprehensive pregnancy and postpartum care for mothers and their babies and will help guide expecting parents who may be at risk for preeclampsia from pre-conception through their childbirth and postpartum recovery.

“This team uses an innovative approach to remotely monitor and treat blood pressures postpartum, allowing early identification and treatment of potential blood pressure problems after childbirth,” she says.