Feeling faint in pregnancy
Why dizziness and faintness are common in pregnancy, the situations that bring them on, when they need urgent attention and what helps.
Very significant changes take place in your cardiovascular system during pregnancy. The heart beats faster, the amount of blood it pumps each minute increases, and the volume of blood circulating through your body rises by 40-45%.
At the same time the blood vessels widen, and that lowers your blood pressure. In the middle of pregnancy, your blood pressure drops to levels you will never see again in your life, before rising once more towards delivery.
Why it happens
In a healthy woman, the cardiovascular and nervous systems adapt to these considerable changes during pregnancy and tolerate them. Sometimes, though, the adaptation is not quick enough and produces dizziness or a feeling of faintness — particularly in the following situations.
Standing up too quickly. While you are sitting, blood pools in the legs and feet. If you stand up quickly, the amount of blood returning from your legs to your heart may not adjust in time. Blood pressure drops suddenly and you feel faint.
Lying on your back. After the second half of pregnancy, the growing uterus reduces the blood returning to the heart from the lower body. Lying on your back makes this worse.
Vasovagal fainting. Some people feel weak while straining, passing urine or opening their bowels. These actions lower blood pressure and slow the heart, producing a feeling of faintness. Pregnant women are more prone to this. Sweating, pallor, nausea, yawning and rapid breathing can accompany it.
Hunger and thirst. Hunger lowers blood sugar and causes light-headedness, and in pregnancy hunger takes effect more quickly. Eat little and often, and keep light snacks with you. A practical way to tell whether your body has enough fluid is to check the colour of your urine. Increase your fluid intake in hot weather and when exercising.
Anaemia. If you are anaemic, you do not have enough red blood cells to carry oxygen, so less blood reaches the brain and the rest of the body — and that brings faintness. The most common cause of anaemia is iron deficiency. Because pregnancy itself predisposes to it, iron supplementation in pregnancy is important.
Excessive heat. Staying too long in a very hot bath lowers blood pressure and can cause faintness.
Rapid breathing. Excessive exercise or anxiety can lead to rapid breathing and then to fainting. Exercise is beneficial, but stop when you feel tired and avoid overdoing it.
When to call your doctor
Do not worry about dizziness or faintness that follows a cause you can identify — heat, hunger, standing up quickly — and take the appropriate precautions. But if the feeling does not pass despite the measures below, or if you experience it often for no reason, do not hesitate to tell your doctor. An underlying cause may be found.
Seek help immediately and go to a medical facility if the faintness followed a blow to the head, or if it is accompanied by severe headache, blurred vision, difficulty speaking, palpitations, numbness, chest pain, breathlessness or bleeding. You may be facing a problem that affects your baby as well as you.
Also, faintness together with abdominal pain in early pregnancy can be a sign of an ectopic pregnancy and requires urgent attention.
What can help
- Lying on your left side increases the blood returning to the heart, increases blood flow to the brain and prevents fainting.
- Avoid getting up suddenly from lying or sitting. If you are lying down, sit up slowly first, wait a few minutes with your legs hanging down, then stand up slowly.
- Standing still for long periods causes blood to pool in the legs; if you must stand for a long time, at least try to keep your legs moving.
- Wearing firm, supportive stockings will help.