ConditionWomen's & pregnancy health
Hypertension of Pregnancy (High Blood Pressure in Pregnancy)
Hypertension of pregnancy is an umbrella term for high blood pressure during pregnancy, defined as 140/90 mmHg or higher. It includes chronic hypertension (present before pregnancy or before 20 weeks), gestational hypertension (new after 20 weeks without organ involvement) and preeclampsia (high blood pressure with signs of organ stress). These disorders affect up to 1 in 10 pregnancies and are a leading cause of complications for mothers and babies. Regular blood pressure checks, low-dose aspirin for those at risk, and timely delivery keep most pregnancies safe.
Also called: Hypertensive disorders of pregnancy, pregnancy-induced hypertension, gestational hypertension, preeclampsia, toxemia (old term)
At a glance
- Definition
- Blood pressure 140/90 mmHg or higher on two readings at least 4 hours apart.
- Types
- Chronic hypertension, gestational hypertension, preeclampsia (with or without severe features), chronic hypertension with superimposed preeclampsia.
- Danger signs
- Severe headache, vision changes, upper right belly pain, shortness of breath, sudden swelling.
- Prevention
- Low-dose aspirin from 12 to 16 weeks for those at high risk.
- Treatment
- Monitoring, blood pressure medicines safe in pregnancy, magnesium for severe preeclampsia, timed delivery.
When to get help
Call 911 or go to the ER
- A seizure in pregnancy or after birth (possible eclampsia). Call 911 or your local emergency number
- Blood pressure 160/110 mmHg or higher on a home monitor
- Severe headache that does not go away with acetaminophen, vision changes (flashing lights, blurring, spots), or confusion
- Pain under the right ribs or in the upper middle abdomen, with nausea or vomiting
- Shortness of breath, chest pain, or trouble breathing when lying down
- Heavy vaginal bleeding or severe constant abdominal pain (possible placental abruption)
See a doctor within a day or two
- Blood pressure of 140/90 mmHg or higher on two readings
- Sudden swelling of the face, hands or around the eyes, or rapid weight gain of more than 2 kg (about 5 lb) in a week
- Reduced baby movements
- Any of these warning signs in the first 6 weeks after delivery
Book a routine appointment
- Planning a pregnancy with chronic high blood pressure, to review medicines
- Discussing low-dose aspirin if you have risk factors for preeclampsia
Types of high blood pressure in pregnancy
| Type | When it starts | Key features |
|---|---|---|
| Chronic hypertension | Before pregnancy or before 20 weeks | Pre-existing high blood pressure; raises preeclampsia risk |
| Gestational hypertension | After 20 weeks | New high blood pressure without protein in urine or organ damage; about a quarter progress to preeclampsia |
| Preeclampsia | After 20 weeks (or up to 6 weeks postpartum) | High blood pressure with protein in urine or signs of kidney, liver, brain, lung or blood involvement |
| Superimposed preeclampsia | Any time in someone with chronic hypertension | Worsening blood pressure or new organ involvement |
| Eclampsia | With preeclampsia | Seizures; emergency |
| HELLP syndrome | Usually third trimester | Hemolysis, raised liver enzymes, low platelets; may have only mildly raised blood pressure |
Some sources use "pregnancy-induced hypertension" for gestational hypertension and preeclampsia together. For details on that framing, see pregnancy-induced hypertension.
Why high blood pressure in pregnancy matters
In preeclampsia, abnormal development of the placenta early in pregnancy leads to the release of substances that damage the lining of blood vessels throughout the mother's body. This causes high blood pressure and can affect the kidneys, liver, brain, lungs and clotting system. Reduced blood flow to the placenta can limit the baby's growth.
Risk factors
High risk (aspirin recommended)
- preeclampsia in a previous pregnancy
- chronic hypertension
- type 1 or type 2 diabetes
- kidney disease
- autoimmune disease such as lupus or antiphospholipid syndrome
- multiple pregnancy (twins or more)
Moderate risk
- first pregnancy
- obesity (BMI over 30)
- age 35 or older
- family history of preeclampsia
- Black race (reflecting social and structural factors)
- IVF pregnancy
- low income
- more than 10 years since a previous pregnancy
Symptoms
Gestational hypertension and early preeclampsia often cause no symptoms, which is why blood pressure and urine are checked at every prenatal visit. Warning symptoms of preeclampsia include:
- headache that does not go away
- vision changes: blurring, flashing lights, light sensitivity
- pain in the upper abdomen or under the right ribs
- nausea or vomiting in the second half of pregnancy
- sudden swelling of the face and hands
- rapid weight gain
- shortness of breath
Mild ankle swelling is common and normal in pregnancy.
Diagnosis
- Blood pressure: two readings of 140/90 mmHg or higher at least 4 hours apart after 20 weeks. 160/110 or higher is severe and needs urgent treatment.
- Urine protein: protein-to-creatinine ratio or 24-hour urine.
- Blood tests: platelets, kidney function (creatinine), liver enzymes.
- Fetal assessment: ultrasound for growth and amniotic fluid, Doppler studies and fetal heart monitoring.
- sFlt-1/PlGF ratio: a blood test used in some centers to predict short-term risk of preeclampsia.
Treatment
Prevention
- Low-dose aspirin (81 mg daily), started between 12 and 28 weeks (ideally before 16 weeks) and continued until delivery, for people at high risk or with more than one moderate risk factor, as recommended by USPSTF and ACOG. Do not start aspirin in pregnancy without discussing it with your prenatal care provider.
- Calcium supplements where dietary intake is low.
Blood pressure control
- Safe medicines in pregnancy include labetalol, nifedipine and methyldopa. ACE inhibitors and ARBs must be avoided because they harm the baby.
- Treating chronic hypertension to below 140/90 mmHg improves outcomes, according to recent trial evidence.
- Home blood pressure monitoring is often recommended.
Preeclampsia management
- Without severe features: close monitoring and delivery at 37 weeks.
- With severe features: hospital care, magnesium sulfate to prevent seizures, IV blood pressure medicines, steroids to mature the baby's lungs if preterm, and delivery at or after 34 weeks, or earlier if the mother or baby is unstable.
- Delivery of the baby and placenta is the only cure for preeclampsia.
After birth
Blood pressure can rise in the first week after delivery, and preeclampsia can even appear for the first time after birth. Blood pressure checks within 3 to 10 days of delivery are recommended. Many blood pressure medicines are compatible with breastfeeding.
Long-term health
A history of hypertensive disorders of pregnancy roughly doubles the later risk of heart disease and stroke, and increases the risk of chronic hypertension, kidney disease and type 2 diabetes. Tell your doctors about it, and have blood pressure, cholesterol, glucose and weight checked regularly.
Frequently asked questions
What is considered high blood pressure in pregnancy?
A blood pressure of 140/90 mmHg or higher on two occasions at least 4 hours apart is considered high in pregnancy. A reading of 160/110 mmHg or higher is severe and needs urgent medical attention.
What is the difference between gestational hypertension and preeclampsia?
Both start after 20 weeks. Gestational hypertension is high blood pressure alone. Preeclampsia is high blood pressure plus protein in the urine or signs that organs such as the kidneys, liver, brain or lungs are affected. Gestational hypertension can progress to preeclampsia.
Can high blood pressure in pregnancy harm the baby?
It can. Reduced blood flow to the placenta may slow the baby's growth, and severe disease can lead to early delivery or placental abruption. With careful monitoring and treatment, most babies are born healthy.
Does high blood pressure go away after pregnancy?
Gestational hypertension and preeclampsia usually resolve within weeks of delivery, though blood pressure can peak in the first week. Chronic hypertension continues. Women who had these conditions have higher long-term heart risk and should keep up regular checks.
Who should take aspirin to prevent preeclampsia?
US guidelines recommend daily low-dose aspirin, starting after 12 weeks, for pregnant people at high risk, such as those with prior preeclampsia, chronic hypertension, diabetes, kidney or autoimmune disease, or twins, and for those with several moderate risk factors. Ask your provider before starting.
Sources
This guide was written from current patient and clinical guidance, including:
- American College of Obstetricians and Gynecologists: Gestational hypertension and preeclampsia (Practice Bulletin 222); Chronic hypertension in pregnancy (Practice Bulletin 203)
- US Preventive Services Task Force: Low-dose aspirin use for the prevention of preeclampsia
- CDC: High blood pressure during pregnancy
- American Heart Association: High blood pressure and pregnancy
- Preeclampsia Foundation: Signs and symptoms