What is blood pressure, and how is it measured?

Blood pressure is the pressure in the arteries in your body. We measure blood pressure by putting a cuff around your upper arm. Then we listen to your blood flow with a stethoscope. High blood pressure is also called “hypertension.”

Why can blood pressure be high in pregnant women?

Three main problems cause high blood pressure in pregnant women:

  1. Chronic hypertension: A woman can have high blood pressure before she gets pregnant. Her high blood pressure is treated with lifestyle changes, like diet and exercise. She might also take medicine. Sometimes a woman has high blood pressure for a long time before she gets pregnant, but she doesn’t know it until her doctor gives her a pregnancy check-up.
  2. Preeclampsia: This condition can cause serious problems for both the mother and the baby. It only happens in the second half of pregnancy. It causes high blood pressure, protein in the urine, blood changes and other problems. We don’t know what causes this condition.
  3. Transient hypertension: Some women just get high blood pressure near the end of pregnancy. They don’t have any other signs of having preeclampsia. These women will have normal blood pressure again after they have their baby.

Why is high blood pressure during pregnancy a problem?

High blood pressure during pregnancy can do different things to you and your baby:

  1. Chronic hypertension: High blood pressure can make your baby grow too slowly. This can hurt your baby’s health. Women with chronic hypertension are also more likely to get preeclampsia, which can be very dangerous.
  2. Preeclampsia: High blood pressure is not the main problem, but it is one of the main signs of this health condition. Preeclampsia can cause problems with your brain (headache and seizures), your eyes (blurred vision), your liver (pain in your belly) and your blood and other organs. It can make your baby grow slowly. If you get eclampsia and seizures, your baby is at risk of dying.
  3. Transient hypertension: This condition does not cause any problems for you or your baby.

How will my doctor treat my high blood pressure while I am pregnant?

The treatment will depend on the reason for your high blood pressure:

  1. Chronic hypertension: If you are already taking medicine for high blood pressure, your doctor may want you to keep taking that medicine. If that medicine is not safe for the baby, your doctor might want you to change to another medicine or to stop taking medicine while you are pregnant. Your doctor will pay special attention to how your baby is growing. You might have ultrasound exams more often. You might have some other tests near the end of your pregnancy to make sure that your baby is healthy. Your doctor will watch closely for signs of preeclampsia.
  2. Preeclampsia: How your doctor treats this condition depends on how close you are to your due date and how you and your baby are doing. The only treatment that stops preeclampsia is to deliver the baby. If your baby has to be born premature, it may have serious health problems. But your doctor may want your baby to be delivered early if you or the baby are too sick. If your doctor thinks it is safe for the pregnancy to go on, he or she will watch you and your baby very closely until delivery. You will see your doctor often in the office and get blood tests. Your baby will also get some tests to make sure the baby is healthy. You might stay home from work and rest in bed.
  3. Transient hypertension: This condition doesn’t need any treatment. But it can be hard to tell this condition from early or mild preeclampsia, so your doctor will watch you very closely to make sure your blood pressure elevation is really due to preeclampsia.

What will happen to my high blood pressure after delivery?

  1. Chronic hypertension: Your blood pressure will probably stay high after you have your baby. You will have to keep taking medicine for high blood pressure, watch your diet and exercise.
  2. Preeclampsia: Your blood pressure will go back to normal within 6 to 12 weeks after you have your baby.
  3. Transient hypertension: Your blood pressure will go back to normal within 6 to 12 weeks after you have your baby. But you are more likely to get chronic high blood pressure later in life.

BARBARA A. MAJERONI, MD, and SREELATHA UKKADAM, MBBS
State University of New York at Buffalo, Buffalo, New York