What to know about high blood pressure during pregnancy
High blood pressure, or hypertension, can occur during the first, second, and third trimester of pregnancy. There are three types of hypertension during pregnancy, and each has slightly different features.
In the United States, high blood pressure occurs in around 6–8% of pregnancies among women who are 20–44 years of age.
Without treatment, this issue, also known as hypertension, can lead to serious health complications for the pregnant person, the infant, or both. But in most cases, hypertension is preventable and treatable.
This article explores the different types of hypertension that can occur during pregnancy, including their risk factors and complications.
Types of hypertension in pregnancy
High blood pressure, for anyone, involves a reading of at least 140/90 millimeters of mercury (mm Hg).
Three types of high blood pressure can occur during pregnancy:
|Type||What it is||When it appears|
|chronic||hypertension that was present before or developed in the first half of a pregnancy||before pregnancy or within the first 20 weeks|
|gestational||blood pressure of 140/90 mm Hg or over in people with:
– no hypertension before pregnancy
– no other heart or kidney disease
– no protein in their urine
|usually appears after week 20 and resolves after delivery but may persist and become chronic|
|preeclampsia||hypertension that appears suddenly alongside protein in the urine and, possibly, other problems||after week 20, often in the third trimester|
What is a healthy blood pressure during pregnancy?
A person with chronic hypertension either had high blood pressure before pregnancy or developed it before week 20, in about the first half of pregnancy.
This type of high blood pressure starts during pregnancy, usually in the second half, or after 20 weeks.
A doctor diagnoses it if systolic pressure is at least 140 mm Hg, diastolic pressure is at least 90 mm Hg, or both.
The person will also have:
- no protein in their urine
- no other heart problem
- no kidney problems
While the rise in blood pressure is usually small, a healthcare professional will likely monitor it every week. If a person’s blood pressure reaches 160/110 mm Hg or higher, serious complications can result.
Gestational hypertension usually goes away after delivery, but it can persist and either become chronic or increase the risk of chronic hypertension later in life.
Preeclampsia involves high blood pressure that occurs during pregnancy or after delivery. It can have severe effects.
This condition usually develops after week 20, often in the third trimester. If it happens before week 34, doctors call it early onset preeclampsia. It may develop in the weeks after delivery, but this is rare.
Experts do not know why some people develop preeclampsia and others do not. The risk may be higher for people who:
- have previously had preeclampsia
- have chronic hypertension
- are carrying more than one fetus
- have kidney disease or diabetes
- have systemic lupus erythematosus, sometimes known as simply “lupus” or SLE
- have a body mass index of 30 or above
- have not been pregnant before, or within the last 10 years
- are aged 35 years or above
- are Black or have a low income, as health inequity can affect the risk
- have a family history of preeclampsia
- have had previous complications during pregnancy
- are pregnant through in vitro fertilization
To diagnose preeclampsia, a doctor will:
- measure blood pressure
- take a blood sample for testing
- test a urine sample for characteristic proteins
Some people have no symptoms. If symptoms occur, they include:
- swelling of the face and hands
- weight gain due to fluid retention
- a persistent headache
- shortness of breath
- vision changes, such as seeing spots
- pain in the shoulder or upper abdomen
People with preeclampsia have a higher risk of a rare but serious medical condition known as HELLP syndrome, which stands for:
- H: hemolysis, which involves the destruction of red blood cells leading to anemia
- EL: elevated liver enzymes, a sign of liver damage
- LP: a low platelet count, which affects blood clotting
Anyone with HELLP needs urgent medical attention.
To reduce the risk of severe complications, a person with preeclampsia may need to deliver early. This can lead to a low birth weight and other health problems for the newborn.
There may also be an increased risk of stroke, kidney disease, heart disease, and hypertension later in life.
Sometimes, preeclampsia is severe enough to cause seizures or a coma due to effects on the brain. In this case, the diagnosis is “eclampsia.” It can occur during pregnancy or within 72 hours after delivery, and it is a medical emergency.
Complications of hypertension for the pregnant person
If hypertension is severe or uncontrolled, it can cause complications during and after pregnancy for the person and their baby. The specific complications depend on the type of high blood pressure.
Having hypertension during pregnancy increases the risk of more serious health conditions later in life, such as chronic hypertension, heart problems, and stroke.
In addition, a person with chronic hypertension before pregnancy has a higher risk of developing preeclampsia and gestational diabetes during pregnancy.
Risks of hypertension for the baby
High blood pressure can increase the risk of health problems for the newborn, such as:
- preterm delivery
- small birth size
- death during infancy
High blood pressure during pregnancy can decrease the flow of nutrients and oxygen through blood vessels, affecting fetal development.
If an early delivery is necessary, this can cause complications such as a low birth weight and difficulty breathing if the baby’s lungs have not yet fully developed.
According to a 2018 review, hypertension can increase the risk of these health conditions for the parent and the child:
- cardiovascular disease
- chronic kidney disease
- other metabolic disorders
What happens if a baby is born at 36 weeks?
Signs and symptoms
The American Heart Association notes that most people with hypertension have no symptoms, so a person may only find out during routine screening.
Monitoring blood pressure is an essential part of prenatal care. Having regular prenatal checkups can help a person keep track of their blood pressure and other vital signs, and access treatment if necessary.
Can you tell if you have high blood pressure?
Risk factors for hypertension
A person cannot alter some risk factors for hypertension, such as:
- having a family history of high blood pressure
- having a disease, such as kidney disease, that increases the risk
- being an older adult, as the blood vessels change over time
- being a Black American
Why are Black Americans more likely to have high blood pressure?
Risk factors that a person can manage to some extent include:
- drinking alcohol
- maintaining a moderate body weight
- having a sedentary lifestyle
- having a diet that is high in salt, sugar, and saturated fats
The best approach depends on the type of hypertension.
- Chronic hypertension: A doctor may recommend continuing to take blood pressure medication during pregnancy, or they may recommend a different medication.
- Gestational hypertension: A doctor may recommend self-care strategies to manage hypertension and will continue to monitor blood pressure and check for preeclampsia.
- Preeclampsia: The healthcare team will monitor the person’s condition and may recommend early delivery, in some cases.
A healthcare professional can recommend ways to manage, and if possible, prevent, high blood pressure before, during, and after pregnancy.
It is not always possible to prevent high blood pressure during pregnancy, but some self-care strategies can help.
- exercising regularly
- having a healthy diet that focuses on whole grains, fruits, and vegetables and is low in salt
- quitting smoking, if applicable, and avoiding secondhand smoke
- limiting alcohol intake, for people who drink
- having regular health checks
- taking steps to reduce stress
- reaching or maintaining a moderate body weight
- managing conditions such as diabetes
Medical professionals tend to recommend regular blood pressure screening, especially for people with risk factors, to detect it early.
High blood pressure is relatively common during pregnancy, and it may develop in people with no history of it. Without appropriate treatment, it can become severe and even life threatening.
Hypertension often causes no symptoms, so it is essential to monitor blood pressure regularly throughout pregnancy.
Having regular prenatal checkups can help prevent high blood pressure from becoming dangerous. If this occurs, the healthcare team can take steps to ensure the safety of the pregnant person and their baby.