Causes of Vaginal Bleeding and Spotting During Pregnancy

By Stacey Feintuch
Reviewed by Alyssa Quimby, M.D.
October 16, 2023
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If you find yourself bleeding during pregnancy, you might become alarmed. But pregnancy bleeding does have many causes, and it isn’t always a sign of trouble.

“In the first three months of pregnancy, bleeding is very common,” says Mary Jane Minkin, M.D., a board-certified ob-gyn at Yale School of Medicine, in New Haven, Connecticut. “About a third of all women will experience it. It may mean absolutely nothing. And half of those who bleed will go on to carry perfectly normal pregnancies.”

Still, bleeding during pregnancy can be a sign of a problem, so it’s something you should take seriously.

Common Causes of Bleeding During Early Pregnancy

Bleeding in the first trimester can signal some frightening issues like:

  • Miscarriage
  • Ectopic pregnancy (when a fertilized egg implants and grows outside the main cavity of the uterus)
  • Molar pregnancy (when an egg and a sperm join incorrectly at fertilization and form a tumor instead of a healthy pregnancy),

But it doesn't always. If you notice bleeding, it’s best to call your provider immediately, but also not to panic, Minkin says. She explains that during the first trimester, other possible bleeding causes could include:

  • Implantation bleeding. This happens when the fertilized egg implants in the lining of the uterus about 10 to 14 days after conception, which is a necessary part of conception.
  • Sexual intercourse. Because the cervix softens during pregnancy, it can be more sensitive and bleed a bit if irritated during sex.
  • A low-lying placenta. This is when the placenta covers the opening of the cervix. “The good news is this usually resolves itself as the pregnancy continues,” Minkin says, adding that your doctor or midwife will continue to monitor that the placenta is moving with ultrasound to be sure.

The blood’s color can give you a clue as to the cause. “Dark brown spotting [during pregnancy] is different from bright red bleeding with clots,” says G. Thomas Ruiz, M.D., a board-certified ob-gyn at Memorial Care in Fountain Valley, California. True bleeding is more of a concern, he says, since it can indicate miscarriage.

Although that sounds very scary, it doesn’t necessarily mean the worst, and it’s always best to call your provider. They will often give you an ultrasound to check whether everything is still healthy.

Other Causes of Vaginal Bleeding During Pregnancy

Some people experience bleeding in the second and third trimesters, as well. Some causes are harmless, but it can also be a sign of something more serious. “Bleeding later in the pregnancy is somewhat less common but does not necessarily mean anything bad,” Minkin says. It’s always worth calling your doctor anytime you experience it or have any other concerning symptoms.

Here are some other possible causes of bleeding during pregnancy:

Placental Problems

A possible cause of bleeding in the third trimester is placenta previa, where the placenta covers the cervix, Ruiz says. He says if your blood is bright red, you should be evaluated right away. Don’t panic, though. He says at 20 weeks about 2% of pregnant people have this condition.

“The majority will resolve itself,” Ruiz says. “You don’t have to do anything.” Your doctor will likely order a follow-up ultrasound to check that it does, he says.

Placental abruption, where the placenta prematurely separates from the uterus’s wall, can also cause bleeding, Ruiz says. This condition is rare in general, but Ruiz notes it can be common among pregnant people who use methamphetamines or cocaine or have conditions like high blood pressure. It can also happen after a trauma, like a fall or car accident.

Preterm Labor

Bleeding can also be a sign of premature labor. So, if they’re concerned that’s a possibility, your provider may want you to get an ultrasound and examine you, but Minkin says that most of the time they will observe you for other signs of labor and not jump into action right away.

Bloody Show

It's common to have light bleeding that is pink or bloody, which is often mixed with mucus, near the end of pregnancy. This is called the bloody show and is often a sign that labor is starting (or starting soon).

Play It Safe: Call Your Provider

If you have bleeding anytime during your pregnancy, don’t ignore it. Reach out to your doctor, who may have you come in for an ultrasound or send you to the hospital to get checked out. “It’s one of those things we want to know about,” Ruiz says. “It’s not one of those things we ignore.”

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