Low blood pressure during pregnancy
7-minute read
If you’re in early pregnancy and you faint or feel very dizzy, this could be a sign of an ectopic pregnancy. This is more likely if you also have bleeding or abdominal pain. If this happens, go straight to your nearest emergency department, or call triple zero (000) and ask for an ambulance.
Key facts
- Your blood pressure is a measure of how strongly your blood pushes against the walls of the blood vessels.
- Low blood pressure during pregnancy is common and not usually a cause for concern.
- Your blood pressure will return to pre-pregnancy levels after you give birth.
- Symptoms of low blood pressure in pregnancy include feeling tired, fatigued and a condition known as syncope (feeling faint and passing out).
- In rare cases, low blood pressure can be dangerous, so it’s important to let your doctor or midwife know if you notice symptoms of low blood pressure.
What is hypotension (low blood pressure) in pregnancy?
Your blood pressure is a measure of how strongly your blood pushes against the walls of the blood vessels.
It’s normally recorded in 2 numbers:
- The top number (systolic) is the pressure when the heart is pumping.
- The bottom number (diastolic) is the pressure in between each beat.
Normal blood pressure in pregnancy is where the top number is below 140 and the bottom number is below 90 — described as '140 over 90'). Blood pressure is measured in units known as ‘millimetres of mercury’ or mmHg.
Having dangerously low blood pressure (hypotension) is uncommon in pregnancy. It’s more common to have high blood pressure, and about 1 in 8 pregnancies will have higher blood pressure than normal. When you are pregnant, your blood pressure is considered high if the top number is 140 or more or the bottom number is 90 or more. High blood pressure is also called hypertension.
It’s common in pregnancy for your blood pressure to fall below normal values in your first trimester, and it continues to go down in your second trimester. Blood pressure rises towards pre-pregnancy levels by the time your baby is born.
What causes low blood pressure in pregnancy?
Your body changes rapidly during pregnancy and some of these changes can affect your blood pressure. When you’re pregnant, blood vessels expand and your heart needs to work harder to ensure healthy blood supply to your growing baby. There are also many hormonal changes that affect your circulatory system. These are just some of the changes that normally happen in pregnancy and cause your blood pressure to temporarily go down from its pre-pregnancy level.
Are there any risk factors for hypotension in pregnancy?
Low blood pressure in pregnancy is more common if you are underweight and if you have low muscle mass (small or weak muscles).
What are symptoms of low blood pressure in pregnancy?
Symptoms of low blood pressure in pregnancy include feeling tired, fatigued and a condition known as syncope (feeling faint and passing out).
How do I deal with dizziness?
Here are some things you can do to avoid feeling faint:
- Try not to stand for long periods of time, but if you need to stand, leg exercises and support stockings can improve your blood flow.
- Stand up slowly after sitting or when getting out of bed or bath.
- Drink plenty of water.
- Have something to eat at regular intervals to keep your blood sugar stable.
- Lie on your side instead of your back.
If you start to feel faint, sit or lie down until the dizziness goes away.
If you’re suffering from nausea and vomiting, speak to your doctor or midwife to find out what treatment might help.
If you are concerned about your symptoms, use healthdirect’s online Symptom Checker to get advice on when to seek medical attention.
CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.
How is low blood pressure diagnosed?
If you’re pregnant, your doctor or nurse will likely check your blood pressure at every antenatal visit.
Your blood pressure reading reveals important information about your health, as well as your baby’s health. The main reason your doctor will measure your blood pressure is to check if you have another condition, like pre-eclampsia.
Blood pressure is dynamic, which means that it can change according to the time of day, after eating, based on your stress levels and during or after physical activity. For this reason, your results reflect your blood pressure at the time your doctor or nurse measures it and may not accurately reflect your true blood pressure. For this reason, your doctor or nurse may take your blood pressure measurement more than once and may take it on both arms. Different equipment may also give different readings.
While your blood pressure is being measured, sit comfortably with your legs resting on a flat surface. Your arm should be resting at the level of your heart. Tell your healthcare practitioner if you are feeling stressed or concerned during your health visit.
Blood pressure is measured with a large inflatable cuff.
How is low blood pressure managed?
Because low blood pressure is a normal part of a healthy pregnancy, you might not need any treatment if your blood pressure drops in the first half of your pregnancy.
If you do notice symptoms of low blood pressure, let your doctor, nurse or midwife know at your next pregnancy check.
Your blood pressure will probably start to return to normal levels on its own during your third trimester.
Are there any risks to me or my baby if I have low blood pressure during pregnancy?
A slight drop in your blood pressure in the first half of your pregnancy is unlikely to increase the risk of problems for you or your baby.
When should I see my doctor?
You can discuss your blood pressure at your regular antenatal checks with your doctor, nurse or midwife. If you feel dizzy or faint, call your midwife, or call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available from 7 am to midnight (AET), 7 days a week (including public holidays).
If you’re in early pregnancy and you faint or are light headed, this could be a sign of an ectopic pregnancy. This is more likely if you also have bleeding or abdominal pain. If this happens, go straight to your nearest emergency department, or call triple zero (000) and ask for an ambulance.
Resources and support
- Read the NSW Health guide to having a baby.
- To find a women’s health doctor near you visit The Royal Australian College Obstetricians and Gynaecologists.
FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.
Do you prefer to read in languages other than English?
- NSW Health also has translated resources in a wide range of community languages.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
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Last reviewed: January 2024
