Pregnancy: Bleeding During the First Trimester (cont.)

Medical Editor:

What are other causes of bleeding during the first trimester?

  • Changes in the cervix. Dr. Ivey explains that pregnancy hormones change cells in the cervix, making them more prone to bleeding. And if you have a cervical polyp (overgrowth of tissue), it's more likely to bleed during pregnancy as well. In both cases, you may experience spotting or light bleeding after having sex or following a pelvic exam.
  • Infection. An infection in the urinary tract or in the pelvic cavity may cause bleeding. It is usually accompanied by discharge, says Ivey .

If your bleeding is more than just light spotting with an obvious reason, your doctor will try to figure out what's causing it by doing a pelvic and abdominal exam, ordering blood tests or doing an ultrasound to check on the pregnancy.

Bleeding can be a sign of these serious, or potentially serious, problems:

  • Threatened miscarriage. If you are bleeding during the first trimester, miscarriage is probably the thing you fear most. In a threatened miscarriage, you bleed and may have mild cramps, but your cervix stays closed. For some women, the bleeding stops, and the pregnancy continues. For others, the bleeding continues, and they eventually have a miscarriage. Ask your doctor if you need to restrict your activities to protect the pregnancy.
  • Miscarriage. Bleeding, abdominal pain, and back pain are common signs of miscarriage. An exam shows that the cervix is open. You may pass tissue through the vagina as well. A miscarriage happens in an estimated 15% to 20% of pregnancies, usually during the first 12 weeks of pregnancy. The most common cause is a genetic problem that interferes with development. In most cases, a miscarriage cannot be prevented.
  • Ectopic pregnancy. Bleeding and abdominal pain can be a sign of an ectopic pregnancy, which happens in about 1 out of 60 pregnancies. An ectopic pregnancy occurs when the egg implants outside of the uterus where it cannot grow. Most of the time, it implants inside the Fallopian tubes. As the pregnancy grows, you may start feeling pain. "Sometimes these pregnancies can actually rupture the Fallopian tube ... at which time a woman could lose a significant amount of blood," says Ivey. In some cases, a blood transfusion and emergency surgery is needed.
  • Subchorionic hemorrhage. In this condition, blood collects between the gestational sac and the wall of the uterus. It's fairly common, says Ivey. Your doctor may see the clot during an ultrasound. Sometimes it dissolves on its own. Or you may pass dark blood.

No matter what the reason, bleeding during pregnancy is scary. If it happens to you, play it safe and call your doctor.

Medically reviewed by Steven Nelson, MD; Board-Certified Obstetrics and Gynecology


American Pregnancy Association: "Bleeding During Pregnancy."

American Pregnancy Association: "Spotting During Pregnancy."

Nemours Foundation: "Ectopic Pregnancy."

Nemours Foundation: "Miscarriage."

R. Todd Ivey, MD, an obstetrician and gynecologist at Texas Children's Pavilion for Women The American College of Obstetricians and Gynecologists: "Bleeding During Pregnancy"

Medically Reviewed by a Doctor on 4/14/2015

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