Abnormal Blood Pressure During Pregnancy

Medically reviewed by University of Illinois-Chicago, College of Medicine on March 16, 2016Written by Kristeen Cherney on March 15, 2012

Blood Pressure and Pregnancy

During pregnancy, your body goes through numerous physical changes to accommodate for 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. Each 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, while readings above 140/90 mm Hg indicate high blood pressure, or hypertension. Hypertension is seen far more often in pregnancy than hypotension.

An abnormal blood pressure reading during pregnancy is certainly 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 the situation.

How to Detect Abnormal Blood Pressure

The AHA defines varying blood pressure readings as follows:

  • In prehypertension, the systolic number is between 120 and 139 or the diastolic number is between 80 and 89.
  • In stage 1 hypertension, the systolic number is between 140 and 159 or the diastolic number is between 90 and 99.
  • In stage 2 hypertension, the systolic number is 160 or higher or the diastolic number is 100 or higher.
  • In a hypertensive crisis, the systolic number is higher than 180 or the diastolic number is higher than 110.

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, is usually defined as 140/90 mm Hg or higher. It may cause:

  • flushed skin
  • swelling of the hands or feet
  • nosebleeds
  • headaches
  • shortness of breath
  • anxiety
  • irritability
  • nausea
  • vomiting
  • changes in vision

Symptoms of Hypotension

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

  • dizziness
  • difficulty concentrating
  • cold, clammy skin
  • blurred vision
  • rapid breathing
  • depression
  • sudden tiredness
  • extreme fatigue

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 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 one out of every three American adults has hypertension. In pregnancy, hypertension is classified as either chronic or gestational. 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.

Gestational hypertension develops after the first 20 weeks of pregnancy. It often occurs as a result of obesity, a lack of exercise, or an unhealthy diet. Though the condition usually goes away after giving birth, your risk of getting hypertension in the future is much higher if you have it.

Hypotension, while 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
  • allergies
  • malnutrition
  • blood loss
  • an infection
  • malnutrition, particularly a lack of folic acid and B vitamins

Treating Abnormal Blood Pressure During Pregnancy

Hypertension must be monitored closely to prevent potentially life-threatening complications. Your doctor will likely recommend frequent fetal monitoring, which requires you to keep track of how often your baby kicks. Little 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. A low-dose aspirin may also be recommended to prevent worsening blood pressure and complications such as preeclampsia.

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
  • take medications, such as fludrocortisone or midodrine
  • wear compression socks
  • consume more salt
  • stand on your feet less
  • take frequent resting 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 complications that are just as serious. Dizziness and fainting increase your risk of falling and injuring yourself or your baby. A significant drop in blood pressure also reduces the amount of oxygen-rich blood circulating throughout your body. This can damage your brain and heart and affect fetal development.

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 lose weight before pregnancy if you’re overweight or obese.

You can also prevent blood pressure problems by:

  • eating a healthy diet during pregnancy
  • limiting your sodium intake
  • managing any preexisting conditions, such as diabetes
  • avoiding 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. For preexisting cases of elevated blood pressure, you’ll likely need to continue taking medications after your baby is born. According to the Mayo Clinic, breast-feeding can help keep your blood pressure from increasing further. However, your doctor might need to adjust your medication to prevent harm to your breast-feeding baby.

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