How to prevent—and treat—high blood pressure during pregnancy

Maintaining a healthy blood pressure is a key marker of overall health, and one of the most important vital signs monitored at each pregnancy visit. High blood pressure, also known as hypertension, can cause serious health problems in people when they are not pregnant—and complications in both the mother and child when it occurs during pregnancy. Hypertensive complications range from more frequent monitoring and medication to life-threatening for both the mother and baby. Complications can be prevented when high blood pressure is detected, aggressively managed, and closely monitored. 

What causes high blood pressure during pregnancy?

Blood pressure changes during pregnancy are normal. Most pregnant women experience a lower blood pressure than usual during their second trimester. This is because during the first trimester pregnant woman make 50% more blood (to help feed the fetus) than when they are not pregnant. Due to this increase in blood volume and dilation of blood vessels, pregnant women may feel lightheaded and tired. Of course, pregnant women may also feel tired because of the work of growing a fetus. Blood pressure may slightly increase during their third trimester. 

While a bit of an uptick is normal at the end of pregnancy, when blood pressure is high, it needs to be managed. The reason for pregnancy-induced hypertension is that “blood volume increases during pregnancy,” explains Alan Lindemann, MD, an obstetrician and maternal mortality expert. “If arteries don’t expand to adjust for the additional volume, blood pressure goes up.” 

Normal blood pressure when not pregnant is lower than 120/80 mmHg, according to the Centers for Disease Control and Prevention. Normal blood pressure for pregnant women can vary from individual to individual, usually from 90/60 to 130/80. 

Variations in blood pressure can be attributed to stress levels, age, and medical history—but measurements should always be below 140/90. Gestational hypertension is a diagnosis of new onset of hypertension (meaning a systolic blood pressure ≥140 and/or diastolic blood pressure ≥90) at more than 20 weeks pregnant. To diagnose gestational hypertension, blood pressure must be elevated at least four hours apart on two or more occasions. If a woman has elevated blood pressure before 20 weeks gestation, then it is considered that hypertension is a pre-existing condition, not related to pregnancy.  Many women do not have medical care when not pregnant and are often unaware of their elevated blood pressure. 

Source: The American College of Obstetricians and Gynecologists

Possible causes of and risk factors for high blood pressure during pregnancy include:

• Pre-existing chronic hypertension
• Hypertension in a previous pregnancy 
• History of preeclampsia
• Stress (or PTSD
• Chronic kidney disease

• Diabetes (including gestational diabetes)
• Patient’s age younger than 18 or older than 40
• Carrying multiples (twins, triplets, etc.)
• Excessive weight gain or obesity
• Family history of gestational hypertension
• Race

What pregnancy complications can high blood pressure cause?

Unfortunately, hypertension in pregnancy causes several serious complications. “High blood pressure during pregnancy can affect the amount of oxygen and nutrients the baby receives, which can affect how the baby grows,” says Cindy M. Duke, MD, an OB-GYN and a clinical assistant professor at the University of Nevada, Las Vegas School of Medicine. Additionally, it stresses maternal blood vessels, increasing the risk of heart disease or stroke in mothers. Gestational hypertension can cause…  

• Induction: Most women want to go into labor naturally, but when high blood pressure is present, uncontrolled, or threatening either of their lives, doctors often induce labor or perform a cesarean section to resolve the condition and save one or both patients. 
• Preeclampsia: This medical condition is when the mother has high blood pressure and elevated protein in urine. It can cause maternal organ damage and is most common after 20 weeks of pregnancy. Untreated preeclampsia can cause serious complications including HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count), which damages red blood cells and interferes with blood clotting, or death to mother and/or child. Preeclampsia can occur within 6 weeks after delivery. Symptoms of preeclampsia include severe headache, nausea, altered mental status, vomiting, upper right belly pain, and general malaise. Call your prenatal care provider immediately if you develop any signs of preeclampsia.
• Eclampsia: Untreated or uncontrolled preeclampsia can progress to eclampsia and cause dangerous seizures in patients that did not have previous seizure conditions. It can be fatal to mother and/or baby. 
• Placental abruption: A placental abruption is when part of the placenta, an organ that develops during pregnancy to supply nutrients and oxygen to the fetus, separates from the wall of the uterus before delivery. This often causes heavy internal or external bleeding in the mother. Subsequent decrease in blood flow to the baby causes a decrease in both oxygen and nutrients for the fetus. Placental abruption can be fatal in both mother and baby unless it is quickly diagnosed and emergently treated with delivery of the fetus and the placenta. Signs include profuse vaginal bleeding or abrupt severe abdominal and back pain. 
• Stroke: “If the blood pressure is not brought under control, you can have a stroke,” warns Dr. Lindermann. Sometimes stroke occurs after uncontrolled preeclampsia or eclampsia. A stroke is when the mother’s brain does not receive blood and oxygen. This deficit of nutrients can be fatal in the short term or cause lifelong disability. 
• Preterm birth: Going into labor before a fetus reaches 37 weeks gestation can be dangerous to the baby as the fetal lungs may be immature or if fetal growth is impaired. . Babies born preterm may have a low birth weight and a more difficult time feeding and thriving. This results in expensive, longer hospital stays and possibly other health issues going forward. 
• Stillbirth: Tragically, a complication of hypertension can be fetal death. 
• Death: Hypertension is the second leading cause of maternal deaths in the U.S. The pregnant woman can die. Women with pregnancy-related hypertension can die even with prompt diagnosis, accurate treatment, and close monitoring. 

Signs of high blood pressure during pregnancy

High blood pressure is called “the silent killer” because often there are no symptoms, however, signs and symptoms of high blood pressure and accompanying conditions include:

• Kidney problems, such as excess protein seen on urinalysis
• Liver problems, like increased liver enzymes seen on blood work
• Decreased levels of platelets in blood 
• Moderate to severe headaches
• Nosebleeds 
• Changes in vision, such as loss of vision, blurred vision, and light sensitivity
• Shortness of breath
• Fluid in the lungs
• Pain in the upper belly, often under the ribs on the right side
• Nausea
• Vomiting
• Anxiety 

“Unfortunately, high blood pressure can happen without feeling any abnormal symptoms,” says Dr. Duke, so it’s especially important to keep up with prenatal appointments and obtain lab work as ordered to better make your medical team aware of impending problems. The goal is to make sure you and your fetus are healthy. 

How to prevent high blood pressure during pregnancy

Since “blood pressure is relative,” Dr. Lindermann says, “There needs to be a baseline for comparison,” so it’s a good idea to have a sense of your usual blood pressure when you are not pregnant. 

Regular monitoring

To prevent high blood pressure complications during pregnancy, the best course of action is to have your blood pressure monitored regularly at prenatal visits, and as recommended by your healthcare professional. Dr. Lindermann even suggests his patients take a blood pressure reading daily and seek medical assistance if there is a large increase. If you are at higher risk of hypertension, ask your provider about more frequent monitoring. 

Healthy diet

Health-promoting behaviors that help keep blood pressure normal include eating a healthy diet.

Some foods known to elevate blood pressure are those with saturated and trans fat, fried foods, fast food, canned, frozen, and processed foods, deli and cured meats, and salty snacks. In addition, you should limit caffeine and soda. Alcohol is prohibited during pregnancy as it can cause birth defects and lifelong fetal issues. 

Exercise

Exercise temporarily elevates your heart rate and therefore your blood pressure, but this is healthy. Maintaining an exercise routine is a good way to keep a healthy blood pressure over time. Many people enjoy prenatal yoga, which is a gentle form of exercise that helps strengthen the changing pregnant body while also promoting relaxation and, therefore, helping lower blood pressure. 

RELATED: How exercise affects your blood pressure

Stress reduction

Stress reduction, via yoga or other meditative or relaxing practices, will also help prevent gestational hypertension. Cutting back on work or other high stressors might be necessary, especially as the due date approaches and the natural stress on the body increases. 

How to lower blood pressure during pregnancy

Once diagnosed with high blood pressure, it’s very important to follow your healthcare provider’s guidance closely. Be aware of your body, watch for concerning symptoms and adopt healthy behaviors. To decrease your blood pressure during pregnancy, many of the same strategies can help.

Healthy diet

If blood pressure is a concern during pregnancy, you may benefit from modifying your diet temporarily or permanently. “Eating a balanced diet and low salt intake can help reduce blood pressure,” says Dr. Duke. While you may have pregnancy cravings for certain foods, your health is of the utmost concern. Moderation is key. 

Exercise

In terms of exercise, Dr. Duke recommends staying active and doing some type of physical activity daily, such as walking or swimming. Again, exercise that balances healthy heart activity and relaxation is important for your health while pregnant and after, when recovery and life-long health are vital as well. Most providers no longer suggest bed rest as a treatment for hypertension. 

Medication

High blood pressure in pregnancy most always needs to be controlled with medications, but some medications are not safe for pregnant women or their fetuses. The blood pressure medications most often prescribed for pregnant hypertensive women include:

• Trandate (labetalol)
• Procardia HL (nifedipine)
• Aldomet (methyldopa)

Your healthcare provider might also have you take daily low-dose aspirin. Always give your medical provider your full health history including all medications and supplements to avoid negative drug interactions. 

Can you have a successful pregnancy with high blood pressure?

Gestational hypertension is fairly common, occurring in about 10% of pregnancies, and medical professionals are used to catching and treating it early. “Even though high blood pressure during pregnancy can cause complications, most women monitored and treated have successful pregnancies and deliveries,” Dr. Duke says. With a combination of frequent and early checks, health-promoting behaviors, and medication if necessary, you can have a successful pregnancy with high blood pressure.