Low blood pressure (hypotension) during pregnancy does not usually cause significant health issues, and most women can treat it at home.
However, very low blood pressure can be a cause for concern, and some women experience bothersome symptoms. In this article, we look at the causes, treatments, and when to see a doctor.
What causes low blood pressure during pregnancy?
Regular health checks with a doctor are recommended during every stage of pregnancy.
Pregnancy causes many changes as a woman's body adapts to the effort it takes to create a baby. This is why it is so important for pregnant women to have regular check-ups with their doctor during all stages of pregnancy.
During these check-ups, doctors will likely ask the woman questions about her lifestyle. The doctor will also check the woman's blood pressure during each visit.
Blood pressure changes slightly depending on a woman's energy levels, nervousness, lifestyle, and stress levels. Blood pressure can also get higher or lower depending on the time of day.
A woman's blood pressure may be lower in the first 24 weeks of pregnancy. This is probably caused by the circulatory system, as blood vessels expand to let blood flow to the uterus.
Other temporary causes also exist, such as standing up too quickly or lying in a hot bath for too long.
While this is common, some other factors can contribute to the issue and cause the blood pressure to drop even lower than usual. For pregnant women, this may include:
- allergic reactions
- prolonged bed rest
- internal bleeding
- heart conditions
- endocrine disorders
It is also possible for some medications to lower blood pressure, so it is vital that pregnant women let their doctor know which medicines they are taking.
Extremely low blood pressure may also be a sign of a complication in early pregnancy, such as ectopic pregnancy, where a fertilized egg implants itself somewhere other than the uterus.
Normal blood pressure levels at stages of pregnancy
During pregnancy, blood pressure is a sign of the health of both mother and baby. Doctors will use the numbers to help diagnose any underlying issues or possible complications.
According to the American Heart Association, normal blood pressure is less than 120 over 80—120 millimeters of mercury (mmHg) is the systolic reading (during contraction of the heart) and is always the top number on the device.
The 80 mmHg is the diastolic reading (when the heart is at rest between beats) and is the lower number on the device. Anything lower than this is considered a low reading but may be normal for many people.
A doctor will usually diagnose low blood pressure when the reading is around 90 mmHg over 60 mmHg.
During the first 12 weeks of pregnancy, a woman might notice a drop in her blood pressure. This low blood pressure will often remain at a low level throughout the first and second trimester and will rise again during the third trimester.
Doctors will continue monitoring blood pressure in the days that follow the birth to look out for any post-pregnancy complications.
Lightheadedness, dizziness, and nausea are symptoms of low blood pressure.
While low blood pressure is usually nothing to be concerned about, the symptoms may be troubling or reduce the quality of life for some women, especially if they have not experienced them before.
Symptoms of low blood pressure include:
- dizziness or confusion
- lightheadedness that may result in fainting, especially after standing up quickly
- general fatigue that may get worse throughout the day
- not being able to catch the breath or taking shallow, rapid breaths
- thirst, even after drinking
- cold, pale, or clammy skin
- vision problems, such as blurred vision or double vision
Any woman who experiences troublesome symptoms such as these should report them to a healthcare professional. They may do some tests to make sure that low blood pressure is the cause and not another underlying condition.
Risks and effects on the baby
One of the primary risks for women who have low blood pressure is falling caused by fainting. Some women with low blood pressure who stand up too quickly after sitting or lying down may faint.
Frequent fainting spells may be dangerous, especially when pregnant. A woman may injure herself if she falls and loss of blood circulation may cause internal issues.
Severe low blood pressure may result in shock or organ damage. It may keep blood from reaching the baby, which poses risks to the baby's health.
According to one study, there is a small amount of research that shows continuous low blood pressure during pregnancy has a negative effect on the outcome of the pregnancy, including stillbirth.
However, there are many other possible reasons for these negative impacts on the baby's health, and low blood pressure alone does not usually have serious complications.
There is usually no medical treatment for low blood pressure during pregnancy, but a woman may try several home remedies to alleviate symptoms. The blood pressure will often return to normal around the third trimester of pregnancy.
However, some women who experience episodes of unusually low blood pressure may require medication. Any underlying conditions that may be causing the drop in blood pressure, such as anemia or a hormonal imbalance, will need to be treated first.
If a doctor suspects that a particular drug is causing low blood pressure, they may offer an alternative medication.
Instead of medical treatment, many women rely on home remedies to help them cope with low blood pressure.
Resting often during pregnancy is recommended, especially with low blood pressure.
When dealing with low blood pressure during pregnancy, it is important to remember to take things slowly.
Taking time to wake up slowly in the morning instead of jumping out of bed, and getting up from the chair or sofa slowly during the day can help prevent dizziness or fainting.
If a woman does feel faint, she should sit or lie down gently to avoid falling and take steady breaths. Lying on the left side may also help increase blood flow to the heart, which may help stabilize the body.
It is also essential for pregnant women to rest often, especially when they have low blood pressure. Getting off the feet and resting periodically throughout the day can give the body time to recover and reduce fatigue.
Wearing loose-fitting, non-restrictive clothing may help avoid dizziness and fatigue as well. Some women might find that wearing compression stockings or snug knee-high socks can help improve circulation.
It is crucial to drink plenty of liquids and to treat any morning sickness or vomiting that is occurring.
If low blood pressure is causing nausea, warm herbal tea may help settle the stomach. Staying hydrated with water can also help.
Doctors may also recommend eating many small meals throughout the day rather than a few large meals. Eating a varied and nutrient-rich diet is especially important during pregnancy and may help reduce symptoms where possible.
A doctor may also recommend that a woman increase her daily salt intake if she is experiencing low blood pressure during pregnancy. Too much salt can have a negative impact, however, so it is essential to speak with a healthcare professional before adding extra salt to the diet.
When to see a doctor
A doctor will usually monitor a woman's blood pressure during regular pregnancy check-ups and offer advice or treatment options if it is too low or high. High blood pressure is a more common problem in pregnancy.
Low blood pressure is normal during pregnancy, but it is important to know when to see a doctor or midwife. Anyone who is having frequent dizziness or fainting spells should seek medical care as soon as possible.
If any woman experiences fainting or dizziness along with a severe headache, vision changes, or shortness of breath, she should seek emergency care. Chest pains and feelings of numbness or weakness one side of the body also require emergency care.
A woman may also want to discuss low blood pressure with a doctor if it persists into the third trimester, or if it continues for an extended period.
If a woman has a history of low blood pressure, she should mention this to the health professional during the initial pregnancy check-ups to ensure the blood pressure does not go too low.
Working with a doctor or midwife to treat the symptoms of low blood pressure during pregnancy can help keep both mother and baby happy and healthy.