Noticed vaginal bleeding during the first trimester of pregnancy? It could be a subchorionic bleed — a condition that should clear up on its own and that usually doesn't pose a risk to you or your baby. Here's what you need to know.

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Key Takeaways
  • A subchorionic bleed (subchorionic hematoma) is a collection of blood between the uterine lining and the chorion or under the placenta, often causing first trimester spotting or bleeding — though some women have no symptoms and it’s found on ultrasound.
  • It’s relatively uncommon, occurring in about 1% of pregnancies, and usually resolves on its own. Most moms-to-be go on to have healthy pregnancies, but your practitioner will monitor it because rare complications can occur.
  • Any vaginal bleeding in pregnancy warrants a call to your provider, who will typically confirm the diagnosis with ultrasound and may recommend activity restriction or pelvic rest until the hematoma clears.

What is a subchorionic bleed?

subchorionic bleed medical illustration

A subchorionic bleed (also known as a subchorionic hematoma) is the accumulation of blood between the uterine lining and the chorion (the outer fetal membrane, next to the uterus) or under the placenta itself. It can cause light to heavy spotting or bleeding, but it may not.

Most subchorionic bleeds resolve on their own, and women go on to have perfectly healthy pregnancies. But because bleeds or clots can rarely cause problems, all subchorionic bleeds are monitored.

How common is it?

Around 1% of all pregnancies have a subchorionic bleed, and it tends to be more prevalent among women who have gotten pregnant through IVF.[1] Subchorionic bleeding is a common cause of first-trimester bleeding and often occurs in uncomplicated pregnancies.

What are the symptoms of a subchorionic bleed?

Subchorionic hematomas can be hard to pick up because they don't always result in noticeable symptoms, especially when they're small. Spotting or bleeding may be a sign, often beginning in the first trimester. But many subchorionic bleeds are detected during a routine ultrasound without there being any noticeable signs or symptoms.

Potential risks of subchorionic bleeding

Remember: The vast majority of subchorionic hematomas dissolve on their own. However in rare cases, a subchorionic bleed can cause the placenta to separate from the uterine wall, and it may be linked to an elevated risk of miscarriage and preterm labor.

That's why it's so important to let your doctor know right away if you ever experience vaginal bleeding during pregnancy.

Should you be concerned?

It's normal and healthy to worry when you notice vaginal bleeding or spotting during pregnancy. But know that subchorionic bleeding usually ends in a healthy pregnancy — and since you'll be checked with ultrasounds until the hematoma reabsorbs itself, you'll get reassurance each time you see fetal cardiac activity at your appointments.

How subchorionic bleeding is diagnosed and treated

If you notice vaginal bleeding during any point of your pregnancy, call your practitioner. They will order an ultrasound. 

Need a little extra support while you wait for answers? The What to Expect app is packed with tools to help you track your pregnancy, stay informed, and connect with a community that’s been right where you are.

Depending on how large the subchorionic hematoma is and where it's located, as well as on your practitioner's preferences, you may be put on activity restriction (also known as bed rest) and asked to avoid sex until the hematoma dissolves and disappears.[2]

The bottom line is that most of the time, this condition is harmless with the right treatment and medical care. So try not to worry, and be sure to tell your doctor about any bleeding you're experiencing.