Lightheadedness During the Third Trimester

pregnant woman feels lightheaded

It is not unusual to experience lightheadedness during the third trimester of your pregnancy. In most cases, this is not a cause for concern and can be easily remedied, however, if your symptoms persist or become more severe, you should call your doctor.

Pregnancy and Your Cardiovascular System

Pregnancy contributes to a number of changes in your body, aside from the obvious expansion of your belly. For example:

  • The blood volume in your body increases by 30 to 50 percent to accommodate your developing baby.
  • Your resting heart rate tends to increase as the heart pumps faster in order to circulate the extra blood.
  • Your heart will pump more blood per minute.
  • Blood pressure may be lower in the first trimester due to hormone and circulatory system changes. However, your blood pressure should return to its normal level by the third trimester.

These cardiovascular changes could potentially be the cause of lightheadedness and other similar symptoms.

Causes of Lightheadedness During Third Trimester of Pregnancy

There are several different factors that can contribute to lightheadedness for a pregnant woman in her third trimester. Luckily, most of them can be easily treated at home.

Hunger or Thirst

If you are not eating enough, this could cause your blood sugar to drop and you may become lightheaded and/or dizzy. This may also happen if you don't drink enough and become dehydrated. You will need to drink at least six to eight (8 oz) glasses of water per day to stay hydrated. It is also a good idea to eat smaller meals more frequently rather than eating three larger meals. You may also want to consider keeping a few healthy snacks and a water bottle with you at all times just in case you begin to feel lightheaded.


Pregnant women who suffer from anemia often feel lightheaded because they have fewer red blood cells to carry oxygen to the brain and other organs. Anemia can happen to anyone, but is more common in pregnant women. It is advised that you eat iron-rich food and take your prenatal vitamins each day. If the prenatal vitamins aren't helping, your doctor may recommend an additional iron supplement.


Some pregnant women find that even moderate exercise can cause them to feel lightheaded. While physical fitness is important, be careful not to overstress your body during the third trimester. Start your workout slowly and take a break if you begin to feel dizzy.

pregnant woman resting from her workout

Getting Overheated

During the third trimester, many pregnant women find that they have a decreased tolerance for heat. Being in a hot room or even taking a hot shower causes them to feel lightheaded. Dressing in layers so you can remove clothing if you start to feel warm is the best way to combat this problem. You may also want to invest in a few extra fans to keep the rooms in your home as cool as possible.

Lying on Your Back

You may want to avoid lying on your back during your second and third trimesters of pregnancy. The weight of the uterus from your growing baby can rest on your inferior vena cava (IVC) and cut off your blood flow. The IVC is the large vein in your body that carries blood from your lower body back to your heart. When your blood flow is cut off, you may become nauseous, lightheaded, suddenly warm and you may even feel like you're going to faint.

This will usually remedy itself and you will feel better once you turn on your side. If you find it difficult to stay lying on your side, you may want to invest in a pregnancy pillow or a body pillow. A pillow placed under your hip or behind you may make this position feel more comfortable.

Standing Up Too Fast

After you've been sitting for a long time, blood starts to pool in your lower extremities. If you move about slowly, this will help the blood vessels pump blood back to the heart, however, if you get up too fast or move suddenly, you may become lightheaded or dizzy. Avoiding sudden movements is a simple remedy for this problem, although wearing support stockings may also be helpful for circulation.

Causes of Fainting in the Third Trimester

There are a number of reasons why you may experience fainting during the third trimester of pregnancy. The most common reasons this may happen include standing for long periods of time and getting up too quickly. Straining during bowel movements and any of the aforementioned causes of lightheadedness may be a cause for fainting as well.

Ways to Prevent Fainting

There are a few things you can do if you begin to feel faint which include:

  • Sit or lie down and lower your head.
  • Open windows to allow air to circulate.
  • Take in deep, steady breaths.
  • Loosen any tight clothing you may be wearing.

In general, you also should also remember to:

  • Avoid getting up quickly.
  • Avoid standing in one position for a long time.
  • Avoid hot showers or baths.
  • Avoid lying on your back.
  • Avoid getting overheated.
  • Eat small, frequent meals.
  • Carry a water bottle with you at all times.

When to Worry

Typically, lightheadedness during the third trimester of pregnancy is a normal symptom that doesn't merit cause for concern. However, you should contact your doctor right away if your lightheadedness is accompanied by the following symptoms:

If you have fallen due to lightheadedness or fainting, you will need to contact your doctor immediately or go to the hospital. While you (the mother), the amniotic fluid and the placenta keep your baby fairly well protected, an examination is still necessary to rule out any possible complications.

Don't Hesitate to Contact Your Doctor

Typically, lightheadedness during pregnancy is a fairly normal occurrence at any stage of pregnancy. However, if you have any concerns about your symptoms, you shouldn't hesitate to give your doctor a call.

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Lightheadedness During the Third Trimester