If you’re pregnant, an abnormal blood pressure raises concern. Talking to a doctor right away can help prevent any health complications for you and your baby.

During pregnancy, your body goes through numerous physical changes to accommodate fetal growth and development. Throughout these nine months, it’s ideal to have a normal blood pressure reading.

Your blood pressure is the force of your blood pushing against the walls of your arteries. Every time your heart beats, it pumps blood into the arteries, which then carry the blood to the rest of your body. The blood typically moves through the arteries at a certain rate. However, various factors can disrupt the normal rate at which blood flows through the vessels, causing an increase or decrease in pressure. Increased pressure in the arteries can result in an elevated blood pressure reading. Decreased pressure in the arteries can result in a low blood pressure reading.

Blood pressure is recorded as two types of numbers. The systolic number is the top number, which indicates the amount of pressure in the arteries when your heart beats. The diastolic number is the bottom number, which indicates the amount of pressure in the arteries between heartbeats. Your blood pressure naturally rises with each heartbeat and falls when the heart rests in between beats. However, the rapid changes your body goes through during pregnancy can greatly influence these numbers and cause a drastic change in blood pressure.

According to the American Heart Association (AHA), a normal blood pressure reading is 120/80 mm Hg and below. Readings below 90/60 mm Hg indicate low blood pressure, or hypotension. Readings above 140/90 mm Hg in pregnancy indicate high blood pressure, or hypertension. Hypertension is seen far more often in pregnancy than hypotension. About 10 percent of all pregnancies in the United States are complicated by high blood pressure issues.

An abnormal blood pressure during pregnancy is a cause for concern. Both you and your baby may be at an increased risk of health complications. However, you may be able to prevent problems by attending regular prenatal appointments so your doctor can monitor your blood pressure closely. You may also want to consider learning more about related conditions so you can help manage factors affecting your blood pressure.

How to detect abnormal blood pressure

The AHA defines abnormal blood pressure readings in non-pregnant adults as follows:

  • Elevated blood pressure is a systolic number between 120 and 129 and a diastolic number lower than 80.
  • In stage 1 hypertension, the systolic number is between 130 and 139 or the diastolic number is between 80 and 89.
  • In stage 2 hypertension, the systolic number is 140 or higher or the diastolic number is 90 or higher.
  • In a hypertensive crisis, the systolic number is higher than 180 and/or the diastolic number is higher than 120.

You may not always be able to tell whether your blood pressure is too high or too low. In fact, hypertension and hypotension may not cause noticeable symptoms. If you do experience symptoms, they may include the following:

Symptoms of hypertension

High blood pressure, or hypertension, in pregnancy is usually defined as 140/90 mm Hg or higher. It may cause:

Symptoms of hypotension

Low blood pressure, or hypotension, is usually defined as 90/60 mm Hg or less. It may cause:

If you suspect you have symptoms of hypertension or hypotension, you should see your doctor right away to help prevent possible complications.

The symptoms of hypertension and hypotension aren’t always present. The best way to know if you have abnormal blood pressure is to take a blood pressure test. Blood pressure tests are often done at regular checkup appointments, and your doctor should perform them throughout your pregnancy.

While these tests are most commonly performed in a medical setting, they can also be done at home. Many local drug stores carry at-home blood pressure monitors that you can use to check your blood pressure. However, make sure to consult with your doctor before you try monitoring your blood pressure at home. Your doctor may have specific instructions regarding when and how often you should check your blood pressure.

Causes of abnormal blood pressure during pregnancy

The AHA estimates that 1 out of every 3 American adults has hypertension. In pregnancy, hypertension can be classified into two main categories: chronic hypertension and hypertension related to pregnancy. Chronic hypertension refers to high blood pressure that was present before pregnancy. You may also be diagnosed with this condition if you develop hypertension during the first 20 weeks of pregnancy. You may still have the condition after giving birth.

High blood pressure disorders related to pregnancy generally develop after the first 20 weeks of pregnancy. There are several types of disorders that range in severity. A 2016 review published in Integrated Blood Pressure Control suggests that age, obesity, and underlying health problems seem to contribute to these conditions. Though these conditions usually go away after you give birth, your risk of getting hypertension in the future is much higher if you develop any of them.

Hypotension, while much less common, can be directly related to pregnancy. Your circulatory system expands during pregnancy to accommodate your fetus. As circulation expands, you might experience a small drop in blood pressure. According to the AHA, this is most common during the first 24 weeks of pregnancy. Still, this amount is usually not significant enough to cause concern.

Hypotension may also be caused by:

  • dehydration
  • diabetes
  • low blood sugar
  • heart problems
  • thyroid problems
  • severe allergic reactions
  • blood loss
  • infection
  • malnutrition, particularly a lack of folic acid, B vitamins, and vitamin D

Treating abnormal blood pressure during pregnancy

Hypertension in pregnancy must be monitored closely to prevent potentially life-threatening complications. Your doctor will recommend frequent doctor visits for fetal monitoring, as well as urine and blood tests. Your doctor will likely ask you to keep track of how often your baby kicks each day. A decrease in movement may be problematic and may indicate the need for an early delivery.

Your doctor will also perform ultrasounds throughout your pregnancy to help ensure that your baby is growing properly. Medications may also be recommended depending on the type and severity of high blood pressure issues you develop.

Mild cases of hypotension usually don’t require treatment. Instead, your doctor may advise you to use caution when standing up so you don’t fall. More serious cases may require you to:

  • drink more fluids, especially water
  • wear compression socks
  • consume more salt
  • stand on your feet less frequently
  • take frequent breaks when standing

Complications of abnormal blood pressure during pregnancy

Hypertension puts you and your baby at an increased risk of complications. These include:

Hypotension can pose challenges to pregnancy. A study published in 2010 showed that nearly half of all cases of hypotension in pregnancy occur in women who already have this condition. This study also reported that women with ongoing hypotension during pregnancy were more likely to have nausea, vomiting, vaginal bleeding, and anemia.

Preventing abnormal blood pressure during pregnancy

The best way to lower your risk of complications is to prevent abnormal blood pressure in the first place. It’s helpful to visit your doctor for a physical exam before becoming pregnant so that any blood pressure abnormalities can be detected early. It’s also best to be a healthy weight before pregnancy.

According to the American College of Obstetricians and Gynecologists, there are no proven methods to prevent high blood pressure during pregnancy. However, you should strive to be in the best possible health before getting pregnant by:

  • eating a healthy diet
  • managing any preexisting conditions, such as diabetes
  • limiting alcohol
  • quitting smoking
  • exercising at least three times per week

Outlook for pregnant women with abnormal blood pressure

Hypertension that develops during pregnancy is often resolved after giving birth. Make sure to attend regular prenatal checkups so your doctor can monitor the health of your baby and look for any signs of abnormal blood pressure. If your doctor prescribes medication to control your blood pressure, make sure to take the medication as directed. For preexisting cases of elevated blood pressure, you’ll likely need to continue taking medications after your baby is born.