Low Blood Pressure During Pregnancy: Definition, Effects and Prevention Tips

You might have heard that a high blood pressure can spell trouble during pregnancy. What does it mean if you have a low blood pressure during pregnancy instead? Let’s look at when and why blood pressure might become low during pregnancy and whether a low blood pressure will affect you or your fetus negatively.

What’s considered normal or low blood pressure during pregnancy

pregnant woman blood pressure doctor

Blood pressure measurements comprise of the systolic and diastolic pressure readings. Systolic pressure refers to the pressure exerted by blood when the heart is pumping, and diastolic pressure refers to the pressure exerted by blood when the heart is resting and not pumping blood. Let’s look at what’s considered normal and low blood pressures.

 

Normal

  • Systolic pressure: less than 120 mm Hg
  • Diastolic pressure: less than 80 mm Hg

This is the ideal blood pressure range. The average blood pressure range is below 120/80, but as this varies during pregnancy, there is no need to be too worried unless the symptoms of low blood pressure are putting you in danger.

 

Mild hypotension

  • Systolic pressure: less than 90 mm Hg
  • Diastolic pressure: less than 60 mm Hg

 

Serious hypotension

  • Systolic pressure: 60 to 89 mm Hg
  • Diastolic pressure: 40 to 59 mm Hg

 

Very serious hypotension

  • Systolic pressure 50 to 59 mm Hg
  • Diastolic pressure: 33 to 39 mm Hg

When might one get low blood pressure during pregnancy?

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Low blood pressure during pregnancy is a phenomenon that usually happens in the first 24 weeks of pregnancy, although some moms continue to have low blood pressure in the third trimester. However, most moms see their blood pressure return to normal levels after week 24.

Causes of low blood pressure (hypotension) during pregnancy

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Dilation of blood vessels

Low blood pressure in the first trimester of pregnancy is due to changes in hormonal levels that cause blood vessels to dilate. This, in turn, causes blood pressure to go down.

 

Underlying health problems

Underlying health problems like a history of low blood pressure, anemia, endocrine problems and heart disorders can be the cause of a low blood pressure during pregnancy. As nutrients in the mother’s body go to the fetus, the mother might develop anemia if she doesn’t take in enough folic acid or vitamins. This can slow blood circulation down and lower blood pressure.

Types of temporary low blood pressure during pregnancy

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Postural hypotension (Orthostatic hypotension)

A temporary form of low blood pressure that takes place in the body when one gets up from a sitting or a lying-down position. This is because after sitting down or lying down for a long time, blood doesn’t have time to reach the brain if you stand up suddenly.

 

Supine hypotension

When you’re lying down in the supine position (on your back), pressure is exerted on the major blood vessels – the aorta, the vena cava and others. This can result in a drop in blood pressure. Supine hypotension usually occurs as a result of the expanding uterus and this can cause dizziness, especially in the second and third trimester.

The risks of low blood pressure during pregnancy

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In the first trimester of pregnancy, not having enough water in your body because of morning sickness or having anemia can cause your blood pressure to drop. When the uterus grows bigger in the second trimester, though, the uterus will compress the blood vessels around it and blood circulation will worsen.

Either one of the aforementioned circumstances can make you feel tired or dizzy, or cause you to have edema. Make sure you take in enough water and iron through your diet.

Conjectures about low blood pressure being a direct risk factor for preterm birth has been shown to be inaccurate as there are other factors that contribute to a premature birth. Low blood pressure is usually associated with women of a smaller build and unable to gain much weight during pregnancy. Thus, there is no concrete evidence to support the thesis that low blood pressure during pregnancy harms the fetus.

However, as the mother might feel dizzy or even have fainting spells due to low blood pressure during pregnancy, this can ultimately affect the growth and the development of the fetus negatively.

Going to the hospital over low blood pressure during pregnancy

pregnant woman hospital doctor

Be sure to seek medical attention if you have severe abdominal pain and dizziness. This could mean that something is wrong, especially if you’re still in the first trimester of pregnancy.

Breathing difficulties (shortness of breath), strong chest pains, excessive vomiting or an abnormally high pulse rate are also signs that indicate your condition is relatively serious and that you should call your doctor as soon as possible.

Even if your symptoms are mild and become better when you drink more water or rest, they could point to underlying health problems that have not yet been discovered. Talk to your practitioner if the symptoms of low blood pressure persist during pregnancy.

How to manage low blood pressure during pregnancy

pregnant woman smile drinking water kitchen

A low blood pressure can be managed with the following changes to diet and lifestyle:

  • Taking in more fluids
  • Increasing salt intake (but be careful not to eat too much either)
  • Having a balanced diet
  • Divide meals into smaller portions and eat more frequently
  • Taking supplements
  • Reduce caffeine intake
  • Wear compression stockings
  • Avoid being on your feet for too long
  • Slowly changing your positions (especially when you’re getting up)
  • Avoid doing activities or exercise that will tire you out quickly

Strive for a normal blood pressure during pregnancy

Low blood pressure during pregnancy is often thought as less dangerous than high blood pressure during pregnancy as it doesn’t seem directly linked to any serious pregnancy complications. However, it is important that you take care of yourself if you have low blood pressure and experience the symptoms during pregnancy. Remember that being at the extreme ends of the blood pressure spectrum isn’t good, and you should strive for a normal blood pressure during pregnancy.