The short answer: In pregnancy, a reading of 140/90 mm Hg or higher is high blood pressure. A reading of 160/110 mm Hg or higher is in the severe range and needs medical care right away. Those are the numbers the CDC and the American College of Obstetricians and Gynecologists (ACOG) use. A high number that comes with a bad headache, vision changes, or upper belly pain is urgent at any reading.

High blood pressure in pregnancy is common. The CDC says hypertensive disorders affect 5% to 10% of women during pregnancy. The National Heart, Lung, and Blood Institute (NHLBI) puts it at 1 in every 12 to 17 pregnant women in the United States.

What numbers count as high blood pressure in pregnancy?

Pregnancy care uses two cut-offs.

  • High: The CDC describes high blood pressure during pregnancy as 140/90 mm Hg or higher on two readings taken 4 or more hours apart.
  • Severe: The CDC describes severe high blood pressure as 160/110 mm Hg on two or more occasions. ACOG defines severe hypertension as a systolic pressure of 160 mm Hg or higher, a diastolic pressure of 110 mm Hg or higher, or both.

These cut-offs are higher than the ones used outside pregnancy. ACOG's patient guidance lists the general adult categories, where stage 1 hypertension starts at a systolic pressure of 130 or a diastolic pressure of 80. Our article on a reading of 130/80 explains those categories.

One reading does not make a diagnosis. ACOG notes that a high reading may be repeated later in the same visit.

Is it chronic hypertension, gestational hypertension, or preeclampsia?

The same number can mean three different conditions. The timing and the other findings decide which one.

  • Chronic hypertension: High blood pressure that was present before pregnancy or that appears before 20 weeks. The CDC adds that high blood pressure which lasts 12 weeks after the birth also counts. ACOG says you have chronic hypertension if you took blood pressure medicine before pregnancy, even if your readings are now normal.
  • Gestational hypertension: A reading of 140/90 mm Hg or higher that first appears after 20 weeks in a woman whose blood pressure was normal before. ACOG says it usually goes away after childbirth, but it may raise the risk of high blood pressure later in life.
  • Preeclampsia: High blood pressure after 20 weeks together with signs that organs such as the kidneys or liver are affected. The CDC says it occurs in about 2% to 8% of all pregnancies. It can lead to seizures, which is called eclampsia.

Chronic hypertension is on the high-risk list for preeclampsia in both the ACOG and USPSTF documents.

At what blood pressure is medication started?

For chronic hypertension in pregnancy, the treatment threshold is now 140/90 mm Hg. That is a change. The older ACOG recommendation was to start medicine only at 160/110 mm Hg.

The change came from the Chronic Hypertension and Pregnancy (CHAP) trial, published in the New England Journal of Medicine in 2022. The trial enrolled 2,408 pregnant women with mild chronic hypertension. One group took blood pressure medicine with a target below 140/90 mm Hg. The other group got medicine only if severe hypertension developed.

  • A serious outcome (preeclampsia with severe features, medically indicated birth before 35 weeks, placental abruption, or fetal or newborn death) occurred in 30.2% of the treated group and 37.0% of the control group.
  • Babies who were small for gestational age made up 11.2% of the treated group and 10.4% of the control group. That difference was not statistically significant.

After the trial, an ACOG practice advisory recommended 140/90 as the threshold to start or adjust medicine for chronic hypertension in pregnancy. ACOG reaffirmed the advisory in March 2025.

ACOG and the cardiology societies use the same number here. According to the American College of Cardiology summary of the 2025 AHA/ACC high blood pressure guideline, treatment is recommended for pregnant women with chronic hypertension when blood pressure reaches 140/90 mm Hg or higher. We could not read the full guideline text, so we cite the summary.

ACOG adds a caution. The CHAP trial tested a threshold to start treatment. It did not set a goal blood pressure, and it did not show how low is too low for the baby's growth.

Which readings and symptoms need same-day or emergency care?

A reading of 160/110 mm Hg or higher in pregnancy, or in the weeks after birth, is an emergency. The NHLBI calls a sudden spike above that level a medical emergency. An ACOG committee opinion says treatment should start as soon as possible, within 30 to 60 minutes of confirmed severe hypertension, to lower the risk of a stroke in the mother. Do not wait for the next clinic visit. Call your obstetric unit or go to an emergency department.

A reading of 140/90 mm Hg or higher that is new for you is a reason to contact your obstetric clinician promptly.

Symptoms matter as much as the number. ACOG says preeclampsia can develop without you being aware of it. The CDC and ACOG list these warning signs:

  • A headache that will not go away
  • Blurry vision, seeing spots, or other changes in eyesight
  • Pain in the upper stomach area or shoulder
  • Nausea or vomiting in the second half of pregnancy
  • Swelling of the face or hands
  • Sudden weight gain
  • Trouble breathing

ACOG says to call your ob-gyn right away if you have any of these. A seizure, chest pain, or severe trouble breathing needs emergency services. Our sibling site symptom.md covers individual symptoms.

Which blood pressure medicines are avoided in pregnancy?

Three drug classes that act on the renin-angiotensin system carry an FDA boxed warning for fetal toxicity:

Each label says to stop the drug as soon as possible when pregnancy is detected. The labels state that these drugs can cause injury and death to the developing fetus.

Do not stop a medicine on your own. Call your prescriber, who can switch you to a different one. The NHLBI names nifedipine, labetalol, methyldopa, and hydralazine as medicines that may be used in pregnancy. Our comparison of blood pressure medications explains how the classes differ.

Does low-dose aspirin prevent preeclampsia?

For some women, yes. The U.S. Preventive Services Task Force (USPSTF) recommends low-dose aspirin (81 mg a day) after 12 weeks of pregnancy for people at high risk of preeclampsia. It is a grade B recommendation.

The USPSTF high-risk list includes a previous pregnancy with preeclampsia, a multiple pregnancy, chronic hypertension, type 1 or type 2 diabetes before pregnancy, kidney disease, and autoimmune disease such as lupus. It says people with two or more moderate risk factors may also benefit.

ACOG's patient guidance says the same and adds one instruction: do not start aspirin on your own.

What happens to blood pressure after the birth?

The risk does not end at delivery. The CDC says postpartum preeclampsia is typically diagnosed within 48 hours after delivery, but it can happen up to 6 weeks later.

ACOG notes that blood pressure often goes up in the weeks after childbirth. It advises women with chronic hypertension to check their blood pressure at home for 1 to 2 weeks after delivery. Our guide to home blood pressure monitoring covers technique. The same warning symptoms apply after the birth, and so does the 160/110 mm Hg emergency level.

There is a long-term effect too. The NHLBI says women who had preeclampsia have a higher risk of high blood pressure and heart disease later in life.

The bottom line

In pregnancy, 140/90 mm Hg or higher is high and 160/110 mm Hg or higher is severe. A severe reading, or a high reading with a lasting headache, vision changes, or upper belly pain, needs care right away. Since the CHAP trial, ACOG recommends treatment of chronic hypertension in pregnancy at 140/90 mm Hg. ACE inhibitors, ARBs, and direct renin inhibitors are not used in pregnancy. Preeclampsia can still start up to 6 weeks after the birth.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your obstetric clinician about any blood pressure reading that worries you, and before you start, stop, or change any medicine or aspirin in pregnancy.