High blood pressure during pregnancy

What is high blood pressure?

Blood pressure is the force of blood that pushes against the walls of your arteries. Arteries are blood vessels that carry blood away from your heart to other parts of the body. Each time your heart beats, it pumps blood to the arteries. If the pressure in your arteries becomes too high, you have high blood pressure (also called hypertension). High blood pressure can put extra stress on your organs. This can lead to heart attack, heart failure, stroke and kidney failure.

Some women have high blood pressure before they get pregnant. Others have high blood pressure for the first time during pregnancy. About 8 in 100 women (8 percent) have some kind of high blood pressure during pregnancy. If you have high blood pressure, talk to your health care provider. Managing your blood pressure can help you have a healthy pregnancy and a healthy baby.

How do you know if you have high blood pressure?

Your blood pressure reading is given as two numbers:

1. Systolic blood pressure. This is the upper (first) number in your reading. It’s the pressure when you heart contracts (gets tight). Your blood pressure is highest when your heart beats and pumps blood.
2. Diastolic blood pressure. This is the lower (second) number in your reading. It’s the pressure when your heart relaxes. Your blood pressure falls because your heart is at rest between beats.

Your blood pressure reading fits into one of five categories:

1. Normal. Your blood pressure is less than 120/80.
2. Elevated. This is when your systolic blood pressure is between 120-129 and your diastolic pressure is less than 80.
3. Stage 1 high blood pressure. This is when your systolic pressure is between 130-139 or your diastolic pressure is between 80-89.
4. Stage 2 high blood pressure. This is when your systolic pressure is at least 140 or your diastolic is at least 90.
5. Hypertensive crisis. This is when your systolic pressure is higher than 180 and/or your diastolic pressure is higher than 120. Call your health care provider right away if your blood pressure is this high.

At each prenatal care checkup, your provider checks your blood pressure. To do this, she wraps a cuff (band) around your upper arm. She pumps air into the cuff to measure the pressure in your arteries when the heart contracts and then relaxes. If you have a high reading, your provider can recheck it to find out for sure if you have high blood pressure. Your blood pressure can go up or down during the day.

What pregnancy complications can high blood pressure cause?

High blood pressure can cause problems for you and your baby during pregnancy, including:

Problems for moms include:

• Preeclampsia. This is when a pregnant woman has high blood pressure and signs that some of her organs, like her kidneys and liver, may not be working properly. Signs and symptoms of preeclampsia include having protein in the urine, changes in vision and severe headaches. Preeclampsia can be a serious medical condition. Even if you have mild preeclampsia, you need treatment to make sure it doesn’t get worse. Without treatment, preeclampsia can cause serious health problems, including kidney, liver and brain damage. In rare cases, it can lead to life-threatening conditions called eclampsia and HELLP syndrome. Eclampsia causes seizures and can lead to coma. HELLP syndrome is when you have serious blood and liver problems. HELLP stands for hemolysis (H), elevated liver enzymes (EL), low platelet count (LP).
• Gestational diabetes. This is a kind of diabetes that only pregnant women get. It’s a condition in which your body has too much sugar (also called glucose). Most women get a test for gestational diabetes at 24 to 28 weeks of pregnancy.
• Heart attack (also called myocardial infarction).
• Kidney failure. This is a serious condition that happens when the kidneys don’t work well and allow waste to build up in the body.
• Placental abruption. This is a serious condition in which the placenta separates from the wall of the uterus before birth. If this happens, your baby may not get enough oxygen and nutrients in the womb. You also may have serious bleeding from the vagina. The placenta grows in the uterus and supplies the baby with food and oxygen through the umbilical cord.
• Postpartum hemorrhage (also called PPH). This is when a woman has heavy bleeding after giving birth. It’s a serious but rare condition. It usually happens 1 day after giving birth, but it can happen up to 12 weeks after having a baby.
• Pulmonary edema. This is when fluid fills the lungs and leads to shortness of breath.
• Stroke. This is when blood flow to your brain stops. Stroke can happen if a blood clot blocks a vessel that brings blood to the brain or when a blood vessel in the brain bursts open.
• Pregnancy related death. This is when a woman dies during pregnancy or within 1 year after the end of her pregnancy from health problems related to pregnancy.

If you have high blood pressure during pregnancy, you’re also more likely have a cesarean birth (also called c-section). This is surgery in which your baby is born through a cut that your doctor makes in your belly and uterus.

Problems for babies include:

• Premature birth. This is birth that happens too early, before 37 weeks of pregnancy. Even with treatment, a pregnant woman with severe high blood pressure or preeclampsia may need to give birth early to avoid serious health problems for her and her baby.
• Fetal growth restriction. High blood pressure can narrow blood vessels in the umbilical cord. This is the cord that connects the baby to the placenta. It carries food and oxygen from the placenta to the baby. If you have high blood pressure, your baby may not get enough oxygen and nutrients, causing him to grow slowly.
• Low birthweight. This is when a baby is born weighing less than 5 pounds, 8 ounces.
• Fetal death. When a baby dies spontaneously in the womb at any time during pregnancy.
• Neonatal death. This is when a baby dies in the first 28 days of life.

What kinds of high blood pressure can affect pregnancy?

Two kinds of high blood pressure that can happen during pregnancy:

1. Chronic hypertension. This is high blood pressure that you have before you get pregnant or that develops before 20 weeks of pregnancy. It doesn’t go away once you give birth. About 1 in 4 women with chronic hypertension (25 percent) has preeclampsia during pregnancy. If you’re at high risk for preeclampsia, your provider may treat you with low-dose aspirin to prevent it.
   
   If you have chronic hypertension, your provider checks your blood pressure and urine at each prenatal care visit. You may need to check your blood pressure at home, too. Your provider may use ultrasound and fetal heart rate testing to check your baby’s growth and health. Your provider also checks for signs of preeclampsia.
   
   If you were taking medicine for chronic hypertension before pregnancy, your provider makes sure it’s safe to take during pregnancy. If it’s not, he switches you to a safer medicine. Some blood pressure medicines, called ACE inhibitors and angiotensin receptor blockers, can harm your baby during pregnancy.
   
   During the first half of pregnancy, blood pressure often falls. If you have mild hypertension and took medicine for it before pregnancy, your provider may lower the dose of medicine you take. Or you may be able to stop taking medicine during pregnancy. Don’t stop taking any medicine before you talk to your health care provider. Even if you didn’t take blood pressure medicine in the past, you may need to start taking it during pregnancy.
    
2. Gestational hypertension. This is high blood pressure that only pregnant women can get. It starts after 20 weeks of pregnancy and usually goes away after you give birth. It usually causes a small rise in blood pressure, but some women develop severe hypertension and may be at risk for more serious complications later in pregnancy, like preeclampsia.

During pregnancy, your provider checks your blood pressure and urine at every prenatal care checkup. She may use ultrasound and fetal heart rate testing to check your baby’s growth and health. Your provider may ask you to check your blood pressure at home and do kick counts to see when and how often your baby moves. Here are two ways to do kick counts:

1. Every day, time how long it takes for your baby to move ten times. If it takes longer than 2 hours, tell your provider.
2. See how many movements you feel in 1 hour. Do this three times each week. If the number changes, tell your provider.

We don’t know how to prevent gestational hypertension. But if you’re overweight or obese, getting to a healthy weight before pregnancy may lower your chances of having this condition. And even though gestational hypertension usually goes away after birth, you may be more likely to develop hypertension later in life. Healthy eating, staying active and getting to a healthy weight after pregnancy can help prevent high blood pressure in the future.

How can you manage high blood during pregnancy?

Here’s what you can do:

• Go to all your prenatal care checkups, even if you’re feeling fine.
• If you need medicine to control your blood pressure, take it every day. Your provider can help you choose one that’s safe for you and your baby.
• Check your blood pressure at home. Ask your provider what to do if your blood pressure is high.
• Eat healthy foods. Don’t eat foods that are high in salt, like soup and canned foods. They can raise your blood pressure.
• Stay active. Being active for 30 minutes each day can help you manage your weight, reduce stress and prevent problems like preeclampsia.
• Don’t smoke, drink alcohol or use street drugs or abuse prescription drugs.

What can you do about high blood pressure before pregnancy?

Here’s what you can do:

• Get a preconception checkup. This is a medical checkup you get before pregnancy to take care of health conditions that may affect your pregnancy.
• Use birth control until your blood pressure is under control. Birth control is methods you can use to keep from getting pregnant. Condoms and birth control pills are examples of birth control.
• Get to a healthy weight. Talk to your provider about the weight that’s right for you.
• Eat healthy foods.
• Do something active every day.
• Don’t smoke. Smoking is dangerous for people with high blood pressure because it damages blood vessel walls.

Last reviewed: February, 2019

See also: Preeclampsia, HELLP syndrome