Lightheadedness During the Third Trimester

pregnant woman with a friend

Lightheadedness during the third trimester of your pregnancy can seem distressing, but this symptom is usually not a cause for concern.

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 amount of blood in your body expands by 40 to 45 percent.
  • Your heart rate increases.
  • Your heart pumps more blood per minute.
  • Blood pressure gradually decreases in the first trimester, but begins to rise again and return to its normal level by the end of the third trimester.

For most women, these changes in the cardiovascular system are barely noticeable. However, occasional lightheadedness may result.

Causes of Lightheadedness During Pregnancy Third Trimester

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

Not getting enough to eat or drink can make you feel dizzy due to low blood sugar and dehydration. You need to drink at least eight ounces of water per day to stay hydrated. Eating throughout the day is a good idea; try having smaller and more frequent meals instead of three larger ones. You may also want to consider keeping a few healthy snacks and a water bottle with you in your purse so you can eat whenever you start to feel lightheaded.


People 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. Remember to 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 excessive exercise causes 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.

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

The ideal position for sleeping, reading, or watching TV during the third trimester is lying on your side. As your baby grows, your uterus slows the circulation in your legs by compressing the vein that returns blood from the lower half of the body to the heart. This causes your heart rate to increase and your blood pressure to drop. Some women even report that lying on their back makes them feel slightly nauseous as well.

If you find it difficult to stay lying on your side, 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, your blood starts to pool in your lower extremities. This can often cause a feeling of dizziness if you stand up suddenly. Avoiding sudden movements is a simple remedy for this problem, although wearing support stockings may also be helpful.

When to Worry

Generally, lightheadedness during pregnancy third trimester 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:

  • Severe headaches
  • Numbness
  • Tingling in the limbs
  • Vaginal bleeding
  • Blurred vision
  • Fainting
  • Impaired speech
  • Heart palpitations

If you have recently fallen and are feeling dizzy, you should make an appointment to speak with your doctor even if you aren't noticing any other symptoms. While the placenta keeps your baby fairly well protected, an examination is still necessary to rule out any possible complications. Depending upon the severity of your fall, lightheadedness could also be a sign of a head injury requiring medical attention.

Lightheadedness During the Third Trimester