Vasovagal Syncope and Pregnancy

Fainting while pregnant

Being pregnant may increase the risk of dizziness and fainting. In many cases, it’s caused by vasovagal syncope, a type of fainting that occurs when blood pressure drops suddenly. You are unconscious for a very short period of time, typically 15 seconds or less.

Sometimes there are warning signs—called a prodrome—that you’re about to faint. They occur about 30–60 seconds before you pass out. Signs include dizziness, nausea, tunnel vision, feeling warm, and sweating.

Vasovagal syncope isn’t usually a sign that something is wrong. The main risk is that you may injure yourself by losing your balance or passing out. Still, you should always contact your doctor if you faint during pregnancy.

Why does pregnancy cause fainting?

Vasovagal syncope happens when you have a sudden drop in blood pressure. During pregnancy, changing hormone levels cause blood vessels to relax and get wider, allowing more blood to flow to the baby. While this is a normal part of pregnancy, it can also lower your blood pressure, which can reduce the flow of blood to your brain and cause dizziness and fainting.

Another change that may contribute to vasovagal syncope during pregnancy is an increase in blood volume. This is also normal during pregnancy. As blood volume increases, it causes the heart to work harder so it can deliver enough oxygen and nutrients to both you and your baby.

What to do if you faint during pregnancy

When you start to feel dizzy, try to quickly lie down and raise your legs. Stay in that position for as long as the dizzy spell lasts. If you can’t lie down, then sit with your head between your legs. Don’t let anyone hold you up in a standing position when you feel warning signs of vasovagal syncope. If you faint, staying upright can lengthen the time that you're unconscious.

Once you’re in a safe place, do movements that encourage blood flow to the brain. These are called isometric counterpressure maneuvers. Examples include:

• Crossing your legs while tensing the muscles in your leg, abdomen, and buttock
• Tightly gripping a rubber ball or similar object
• Tightly gripping one hand with the other while pulling them against each other

When to call a doctor

Even though vasovagal syncope is usually not a sign of something serious, you should contact your healthcare provider if you are pregnant and faint. They may want you to examine you and make sure you don’t have any underlying conditions that are contributing to the fainting.

Call your provider right away if the dizziness is persistent or if you feel dizzy and also have palpitations (fast, fluttering, or pounding heartbeat), blurred vision, or headaches.

Go to the ER if you faint and have any of the symptoms below, which may be signs of ectopic pregnancy, a low-lying placenta, or placental abruption:

• Vaginal bleeding
• Abdominal pain

How to prevent fainting

• Stand up slowly when getting up from sitting or lying down. Getting up too quickly can cause a sudden drop in blood pressure, leading to dizziness and fainting.
• Don’t stand for long periods of time. If you have to stand, try to keep your feet moving to help circulation.
• Wear compression stockings. These help prevent vasovagal syncope by compressing the legs to keep blood flowing to the heart.
• Don’t go too long without eating. Delaying or skipping meals lowers your blood sugar and increases the risk of fainting. You may find that eating smaller meals more often throughout the day—instead of three large meals—helps keep your blood sugar steady.
• When you are in the middle of the second trimester, don’t lie on your back. The weight of the growing uterus presses on the blood vessels, slowing circulation in your legs and lowering blood pressure.
• Avoid hot, stuffy spaces and use warm water instead of hot water when you shower. Heat and hot water widen blood vessels, increasing the risk of dizziness and fainting.
• Drink plenty of water and eat foods with a high water content, like watermelon and cucumbers, to avoid dehydration.

Should I be worried?

In general, there’s no reason to panic. A study published in the Journal of the American Heart Association did show that fainting during pregnancy, especially during the first trimester, is linked to an increased risk of complications like premature delivery, birth defects and, in mothers, abnormal heart rhythms and further episodes of fainting. The fainting itself may not be the cause of the complications, but that it may be a sign of an underlying condition.

Most important is that you tell your provider if you faint. They may want to do some testing and monitor your pregnancy more closely.