High blood pressure during pregnancy
Your blood pressure reading is given as two numbers: the top (first) number is the pressure when your heart contracts and the bottom (second) number is the pressure when your heart relaxes. A healthy blood pressure is 110/80. High blood pressure happens when the top number is 140 or greater, or when the bottom number is 90 or greater.
High blood pressure can stress your heart and cause problems during pregnancy. 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.
What kinds of high blood pressure can happen during pregnancy and how are they treated?
There are four main kinds of high blood pressure during pregnancy:
- Chronic hypertension. This is high blood pressure you already have before you get pregnant or that develops before 20 weeks of pregnancy. It doesn’t go away once you give birth.
During pregnancy, your health care provider makes sure your blood pressure is under control. Without treatment, chronic hypertension can lead to health problems like heart failure or stroke. He also checks for signs of preeclampsia.
Your provider changes any medicine you take if it’s not safe for your baby. Some blood pressure medicines, called ACE inhibitors and angiotensin receptor blockers, can harm your baby during pregnancy. You may be able to stop taking your medicine during the first half of pregnancy. Blood pressure tends to fall during this time. Don’t stop taking any medicine, though, before you talk to your health care provider.
Your provider may use ultrasound and fetal heart rate testing to check your baby’s growth and health. You may need to give birth early if your hypertension gets worse or if you go on to have preeclampsia.
- Preeclampsia. This is a high blood pressure that only pregnant women can get. It happens when you have both high blood pressure and protein in your urine. It usually starts after 20 weeks of pregnancy and goes away after you give birth.
Preeclampsia can be a serious medical condition. In rare cases, it can become a life-threatening condition called eclampsia. Eclampsia causes seizures and can lead to coma. Even if you have mild preeclampsia, you need treatment to make sure it doesn’t get worse. Without treatment, preeclampsia can cause kidney, liver and brain damage. Treatment depends on how severe your preeclampsia is. Treatment can range from careful monitoring by your provider to inducing labor.
- Gestational hypertension. This is high blood pressure that only pregnant women can get. Unlike preeclampsia, women with gestational hypertension don’t have protein in their urine. This condition starts after 20 weeks of pregnancy and goes away after you give birth. Some women with gestational hypertension have preeclampsia later in pregnancy.
We don’t know how to prevent gestational hypertension. But if you’re overweight or obese, reaching a healthy weight before pregnancy may lower your chances of having this condition.
During pregnancy, your provider checks your blood pressure and urine at every prenatal visit to monitor your hypertension. She may use ultrasound and fetal heart rate testing to check your baby’s growth and health.
- Chronic hypertension with preeclampsia. About 1 in 4 women with chronic hypertension (25 percent) have preeclampsia later in her pregnancy.
During pregnancy, your provider montiros your conditiona at every prenatal visit. She may use ultrasound and fetal heart rate testing to check your baby's development.
What pregnancy complications can high blood pressure cause?
If you have high blood pressure during pregnancy, your provider can help you manage most health problems through regular prenatal care. Pregnant women with high blood pressure are more likely than women without high blood pressure to have these complications:
- Low birthweight. This is when a baby weighs less than 5 pounds, 8 ounces. High blood pressure can narrow blood vessels in the uterus (womb). Your baby may not get enough oxygen and nutrients, causing him to grow slowly.
- Premature birth. This is birth that happens too early, before 37 completed 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.
- Placental abruption. In this condition the placenta separates from the wall of the uterus before birth. It can separate partially or completely. If this happens, your baby may not get enough oxygen and nutrients. Vaginal bleeding is the most common symptom of placental abruption after 20 weeks of pregnancy. If you have vaginal bleeding during pregnancy, contact your health care provider immediately.
How is high blood pressure diagnosed during pregnancy?
Most women with high blood pressure during pregnancy have no symptoms. So it’s important to go to all your prenatal care visits. Your provider measures your blood pressure and checks your urine for protein at every visit. If you have high blood pressure, your provider can help you manage it.
What can you do about high blood pressure before pregnancy?
If you have chronic hypertension before pregnancy, go for a preconception checkup before you try to get pregnant. Making healthy choices before pregnancy can help you manage your blood pressure. For example, do something active and eat healthy foods every day to help you get to or stay at a healthy weight. If you smoke, quit. Smoking is dangerous for people with high blood pressure because it damages blood vessel walls. Making these changes can help you have a safer pregnancy.
Last reviewed March 2012
See also: HELLP syndrome, Preeclampsia