Chronic Hypertension

Last Update: 07 Apr 2026

Condition

Table of content

1. What is it? 2. Why managing? 3. Non-Medical Options 4. Medications 5. Breastfeeding/ chestfeeding 6. Key Takeaways 7. Limits of Research

Welcome to our Fact Sheet on chronic hypertension during pregnancy and lactation. The information is based on current research and may evolve with new scientific knowledge. This content does not replace personalized advice your healthcare professionals.

1. What is chronic hypertension?

Chronic hypertension is defined as high blood pressure that existed before pregnancy or was present before 20 weeks of pregnancy. High blood pressure means that the force of blood pushing against your artery walls is higher than it should be and stays that way over time.

If you develop high blood pressure after 20 weeks of pregnancy, it is gestational hypertension or preeclampsia. You can read more about these conditions here.

Blood pressure is evaluated with two numbers. The first number represent the pressure in blood vessels when the heart beats while the second is the pressure when the heart rests between beats. In pregnancy, blood pressure is considered high when the two numbers are 140/90 mmHg or higher, confirmed by two separate readings 15 minutes apart.

Very high blood pressure (160/110 mmHg or higher) can cause headaches, blurred vision, chest pain and other symptoms. But most people with hypertension don’t feel any symptoms. The only way to know if you have hypertension is to measure your blood pressure at home, at the pharmacy and at your regular prenatal checkups.

If you have high blood pressure and are planning a pregnancy, or recently found out you’re pregnant, it’s a good idea to discuss with your healthcare provider to adjust your treatment if needed.

2. Why is it important to manage chronic hypertension during pregnancy?

If chronic hypertension is not well controlled during pregnancy, it can increase risks of complications for both you and your baby. But don’t worry, by measuring your blood pressure regularly and managing your treatment, most people can have safe pregnancies and healthy babies.

Understanding Pregnancy Risks

Research helps us estimate the risks linked to common pregnancy-related conditions. Miscarriages (loss of the baby), congenital malformations (birth defect, malformation present at birth), premature birth (before 37 weeks), and other complications can happen in any pregnancy for many reasons. This is the background risk. Research helps us understand if these risks are higher when chronic hypertension is not managed during pregnancy.

It’s also important to remember:

Some risks are well studied, while others need more research.
Your personal risk depends on other factors like your age, medical history, genetics, lifestyle (such as smoking or alcohol use), and other health conditions.

Based on current research, chronic hypertension can increase risk of preeclampsia and eclampsia for the pregnant person because the high blood pressure puts extra strain on the heart and blood vessels, raising the chance of organ damage. This extra pressure on the blood system can also increase the risk of complications with the placenta like placental abruption (when the placenta detaches too early).

For the baby, hypertension can reduce blood flow to the placenta, which may lead to lower birth weight, slowed growth, or preterm birth.

The table below provides a summary of what research says about those risks.

Table 1. Possible risks of unmanaged chronic hypertension during pregnancy.

Who?	What?	What does research say?
Pregnant person	Fertility (ability to get pregnant)	More research needed to understand if there’s an impact.
	Miscarriages	Very few studies found an increased risk of miscarriage with pre-existing hypertension. More research is needed to confirm the risk.
	Caesarean delivery	Slightly increased risk of having a caesarean delivery.
	Superimposed preeclampsia	Increased risk of developing preeclampsia with chronic hypertension.
	Placental abruption	Increased risk that the placenta detaches from the uterus.
	Health complications	The higher the high blood pressure is, the higher are the long-term health risks like kidney damage, stroke or other brain blood-vessel problems.
Unborn baby	Congenital malformations	There’s are worries about an increased risk of certain malformations like heart, renal, limp defect.
	Premature birth	Slightly higher risk of preterm birth (before 37 weeks).
	Low birth weight	Slight increased risk of low birth weight (less than 5 pounds and 8 ounces [2,500g]).
	Stillbirth	Slightly increased risk compared to the background risk, remain rare.
Future child	Brain development	Studies are conflicting on the risk of autism spectrum disorder and ADHD. More research is needed to evaluate this risk.
Future child	Long-term health issues.	More research needed to evaluate this risk.

*These findings describe patterns seen in research studies of many pregnancies. They do not predict what will happen in any one pregnancy.

3. What can I do to manage my chronic hypertension other than medications?

Managing high blood pressure in pregnancy often starts with medications. However, combining treatments with healthy daily habits can make a big difference for your well-being.

Stay active: Aim for about 150 minutes of moderate activity each week (as recommended by your healthcare provider). This could include brisk walking, water aerobics, light resistance training, or even household activities like gardening.
Maintain a healthy weight: Reaching and keeping a healthy weight before and during pregnancy can lower your risk of complications.
Lower stress: Relaxation techniques like deep breathing, meditation, or gentle prenatal yoga may help reduce blood pressure.
Avoid smoking and alcohol: Both increase risks during pregnancy and can make high blood pressure harder to manage.

These steps, along with regular prenatal care, can help manage hypertension and reduce risks for you and your baby. Your healthcare provider will work with you to create a plan that fits your needs.

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4. Medications prescribed to manage chronic hypertension

Medications that help lower blood pressure are called antihypertensives. During pregnancy, a healthcare provider may prescribe an antihypertensive to manage hypertension. The best choice depends on factors like other medical conditions, side effects, and others. The medication and its dose can also change throughout the pregnancy. Make sure to talk with a healthcare provider to find the best option for you.

Along with medication, preventive steps can also help. For example, calcium supplements may help lower the risk of preeclampsiafor people who do not get enough calcium in their diet (less than 900mg/day). In this situation, Canadian guidelines suggest calcium supplementation (at least 1,000 mg/day) if advised by your healthcare provider.

What does research say?

According to the Society of Obstetrician and Gynaecologists of Canada (SOGC), antihypertensive medications used in pregnancy can be grouped into first and second line treatments. These are fairly well studied, and none of these antihypertensive have been proven to increase risk of malformations.

First-line treatments: These medications are most used because they work well and are generally considered safe for pregnancy. They are usually given as monotherapy meaning only one medication at the time is prescribed.
- Oral labetalol (a beta-blocker) is generally the first and most common option.
- Oral long-acting nifedipine (a calcium channel blocker)
- Oral methyldopa (an alpha-2 agonist, less common but sometimes used)
- Other oral beta-blockers (e.g. propranolol)
Second-lines options: These may be used if first-line options aren’t suitable, but they can have more side effects:
- Thiazide diuretics (e.g. hydrochlorothiazide)
- Clonidine
- Hydralazine (only given in hospital)

In some situation, if taking one medication is not enough to lower your blood pressure, your healthcare provider might prescribe a combination of two.

Other medications exist to treat hypertension, but they are usually avoided or switch during pregnancy due to risks (e.g. low birth weight), limited safety data, or other concerns. These can include:

Angiotensin-converting enzyme (ACE) inhibitors (e.g. enalapril, lisinopril, ramipril): can affect the baby’s kidneys and amniotic fluid, especially in the 2nd or 3rd trimester.
Angiotensin-receptor blockers (ARBs) (e.g. losartan, valsartan): similar concern for the baby’s kidneys and amniotic fluid, especially in the 2nd or 3rd trimester.
Amlodipine, a calcium channel blocker, is not often given during pregnancy because there isn’t enough data.
Atenolol as some studies link early use to lower birth weight.

If you become pregnant (or planning a pregnancy) while taking a medication usually avoided, it’s important to talk to your healthcare provider and not stop it on your own. Sometimes a person may stay on a medication with closer monitoring, depending on their medical needs.

It’s important to always talk to your healthcare provider before starting or stopping any medication during pregnancy to find the best option for you and your baby

The table below lists some of the most common types of medications used in Canada to treat hypertension. To learn more about a specific medication, please consult the associated Fact Sheet.

Table 2. Some medications available in Canada to treat chronic hypertension during pregnancy.

Medication Types	Medication Names	Brand names
Beta-Blockers (first-line)	Oral labetalol	e.g. Apo-labetalol®, Riva-labetalol®, Trandate®
	Acebutolol	e.g. Monitan®, Sectral®
	Metoprolol	e.g. Lopressor®, Betaloc®
	Pindolol	e.g. Visken®
	Propranolol	e.g. Hemangiol®
Alpha-2 Agonists	Methyldopa (less common)	e.g. Aldomet®
Alpha-2 Agonists	Clonidine (second-line)	e.g. Catapres®
Diuretics	Hydrochlorothiazide (second-line, less common)	e.g. HydroDiuril®
Diuretics	Indapamide	e.g. Lozide®

* Always valid with a healthcare professional before using medication during pregnancy.

How do I know which medication to take?

Each medication has its benefits and disadvantages, and your healthcare team (pharmacist, nurse, doctor, midwife) is best equipped to guide you in making an informed decision adapted to your specific needs. For more information about specific medications or other preventive steps, talk to your healthcare provider.

5. Can high blood pressure or its treatment affect breastfeeding milk supply (lactation)?

If you have chronic hypertension, you can still breastfeed or chestfeed if this is your choice. Lactation, so making and releasing milk from your breast, is possible for people with high blood pressure and may even bring additional health benefits.

If you take medication for your blood pressure, most options – including labetalol, methyldopa, nifedipine, enalapril, captopril- are considered compatible with lactation because only very small amounts pass into human milk. Your healthcare provider can help choose the medication that works best for you while breastfeeding or chestfeeding, to keep both you and your baby safe.

If you have any concerns or questions about lactating, don’t hesitate to talk to your healthcare professional (doctor, nurse, pharmacist) or a lactation consultant from your region (e.g. Canadian Lactation Consultant Association).

Key Takeaways

Chronic hypertension, also called high blood pressure, is when the pressure in your blood vessels is higher than 140/90 mmHg before 20 weeks of pregnancy.
If left untreated, chronic hypertension can increase the risk of preeclampsia, preterm birth, low birth weight, or, in rare cases, serious complications for the pregnant person.
While a healthy lifestyle can help reduce your blood pressure, during pregnancy, a medication is often prescribed to protect you and the baby.
First-line options include labetalol, methyldopa, or long-acting nifedipine are often used during pregnancy as they have been well-studied and not proven to increase risk in pregnancy.
Lactating is possible for most people with chronic hypertension, even when taking medications. Many are considered compatible with lactation as only a very small amount pass into the milk.
Always talk with healthcare professionals before starting, changing, or stopping medications.

Research Is Great, But It Is Not Perfect

Making informed health decisions also means understanding what research knows and what it cannot say. Here’s what our experts have found about the research on chronic hypertension during pregnancy:

Several studies: Many studies have been done which make the clinical guidelines easier to rely one.
Limited diversity: Many studies are from wealthier countries, which may not reflect experiences in other parts of the world.

These observations highlight the need for larger, more diverse, and long-term research to improve care for pregnant people with hypertension.

References

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