Pregnancy can involve quite a bit of lab work and monitoring of certain vital signs. One of those key vitals to keep track of is blood pressure.
Blood pressure is monitored closely in pregnancy, but what happens when it's too high or low? Learn the signs and symptoms of low and high blood pressure, what you can do to manage blood pressure during pregnancy, and when you need to get care right away.
Before we get into it, let’s briefly review what blood pressure numbers actually mean.
What is blood pressure?
Blood pressure is the force of your blood as it pushes against the walls of your arteries while your heart pumps. A blood pressure reading is recorded as two numbers followed by “mmHg”. The mmHG is a measurement of pressure that stands for millimeters of mercury. For example, a reading looks like this: 110/80 mmHg. The two numbers include systolic and diastolic blood pressure:
- Systolic: the top number which indicates the amount of pressure in the arteries when your heart beats.
- Diastolic: the bottom number which indicates the amount of pressure in the arteries between heartbeats.
Your blood pressure naturally rises with each heartbeat and falls when the heart rests in between beats. It’s normal for blood pressure to fluctuate throughout the day, and external factors, like periods of stress or excitement can cause temporary changes.
How does blood pressure change in pregnancy?
When you’re pregnant, your body goes through a number of drastic changes, and your entire circulatory system expands quickly. This expansion often causes a drop in blood pressure in the first 24 weeks of pregnancy, but the body typically adapts and blood pressure normalizes again toward the end of pregnancy.
However, for some women, rather than normalizing, blood pressure stays low or rises above ideal levels. Blood pressure that is either too high or too low can cause some discomforts and risks in pregnancy.
When it’s too low
In general, the lower your blood pressure, the better. However, as with most things, there is generally a happy medium, and both too high and too low can be problematic. Some organizations have a defined level at which they consider blood pressure officially low (hypotension) – at or below 90/60 mmHg. If your blood pressure is consistently around this level and you aren’t experiencing any symptoms, your provider may not have any concerns. However, it’s still wise to rule out any potential underlying causes that could affect the health of you or your baby. We’ll discuss these below.
Low blood pressure can come with a number of symptoms, including dizziness or lightheadedness, fainting, nausea, dehydration and unusual thirst (note, dehydration can also sometimes cause blood pressure to drop, resulting in a tough cycle to break), lack of concentration, blurred vision, cold or clammy skin, rapid and/or shallow breathing, fatigue, and depression.
Since many of these can be common pregnancy symptoms, they might be tough to identify as related to low blood pressure. Your provider will likely check blood pressure at your appointment anyway, but still be sure to mention any symptoms to your provider. Don’t be afraid to reach out between appointments with concerns.
There are also several factors that can contribute to low blood pressure that come with their own set of risks. Even if you aren’t experiencing uncomfortable symptoms, it's important to rule out any of these possible root causes to ensure that you aren’t missing a condition that should be managed:
- Internal bleeding
- Prolonged bed rest
- Certain medications
- Heart conditions
- Endocrine disorders
- Kidney disorders
- Nutritional deficiencies (Folate, Iron, and Vitamin B12)
- Allergic reaction
- What you can do
If you aren’t experiencing any symptoms of hypotension, you may not need to change anything. However, if you are experiencing symptoms, you can take the following steps to help manage them:
- Stand up slowly from sitting or laying
- Drink more water
- Add electrolytes (salt, potassium, magnesium, etc.) to water
- Wear compression socks
- Take time to cool down from exercise (don’t just stop abruptly)
- Check levels of Vitamin B12, Folate, and Iron
- Get your thyroid checked
When it’s too high
Blood pressure readings above 140/90 mmHg in pregnancy indicate high blood pressure, or hypertension. Hypertension is seen far more often in pregnancy than hypotension, and research suggests that about 10 percent of all pregnancies in the United States are complicated by high blood pressure issues.
Slightly high blood pressure often doesn't cause symptoms. This is why it is important to go to all of your scheduled prenatal visits – blood pressure monitoring allows your provider to identify any potential problems, hopefully before they become complications. Some women do experience symptoms, which may include the following:
- Flushed skin
- Swelling of the hands or feet
- Mild headaches
- Shortness of breath
- Abdominal pain
- Nausea or vomiting
Very high blood pressure, known as preeclampsia, can be quite dangerous and can cause the following symptoms:
- Severe headache
- Blurry vision
- Pain in your upper belly
- Rapid weight gain—more than 2 pounds in a week or 6 pounds in a month
- Protein in your urine
Tell your provider right away if you experience any of these symptoms. It’s important to be closely monitored in the case of preeclampsia. Don’t attempt to manage very high blood pressure on your own.
High blood pressure during pregnancy can be a first sign of preeclampsia. Again, this condition can be dangerous for both mama and baby – it is not something to try to manage on your own.
Preeclampsia can put you and baby at increased risk for a preterm delivery, C-section delivery, fetal growth restriction, placental abruption, eclampsia (a more severe case that involves seizures), and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count) - a potentially life-threatening condition.
- What you can do
Since high blood pressure can be a sign of preeclampsia, it’s important that you monitor your blood pressure closely. Having high blood pressure during pregnancy doesn't mean that you will get preeclampsia. But it does mean that you need to have your blood pressure checked often.
There are other ways to manage high blood pressure in pregnancy. But again, if you suspect or have been diagnosed with preeclampsia, don’t attempt to use these techniques to manage blood pressure on your own.
- Aim for healthy weight gain: weight gain is a sensitive topic in pregnancy, but supporting healthy weight gain by focusing on balanced habits like eating well and moving regularly can help to manage high blood pressure.
- Incorporate daily movement: with your provider's approval, regular exercise can be a great way to manage elevated blood pressure. Movement can have many other benefits, like improving constipation, managing stress, improving circulation, and Walking or swimming several times a week can help lower blood pressure. And it's good for you and your baby.
- Manage stress: This may be hard to do, especially if you continue to work, have young children, or have a hectic schedule. But try to find some time to relax. We like the Expectful app as a resource for guided meditations focused on the perinatal life stage.
- Monitor your blood pressure and keep an eye out for symptoms of preeclampsia: the biggest risk to elevated blood pressure in pregnancy is escalating to preeclampsia, so be sure to go to all of your prenatal checkups and consider monitoring your blood pressure at home if your provider recommends or if you think it would help to manage any stress and anxiety around the condition (you know yourself best here!).
- Don't smoke: This probably goes without saying, but be sure to avoid smoking yourself, and avoid exposure to secondhand smoke as much as possible.
Your body is going through a tremendous amount of changes during pregnancy. It can be hard to separate out normal pregnancy discomforts from true concerns, like those associated with blood pressure changes.
When in doubt, reach out to your provider and advocate for your health by requesting whatever additional testing or support would make you feel comfortable and confident. Your health and your baby’s health are worth it!