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By Mayo Clinic staffVaginal bleeding during pregnancy has many causes. Some are serious, and some aren't.
First trimester
Possible causes of vaginal bleeding during the first trimester include:
- Cervical cancer
- Cervical changes, including more blood flow to the cervix and softening of the cervix, which may result in harmless vaginal bleeding after sex or a pelvic exam
- Ectopic pregnancy
- Implantation bleeding
- Miscarriage
- Molar pregnancy
- Some cervical infections
Second or third trimester
Possible causes of vaginal bleeding during the second or third trimester include:
- Miscarriage
- Placenta previa
- Placental abruption
- Premature opening of the cervix (cervical insufficiency), which can lead to preterm birth
- Preterm labor, which may result in light bleeding — especially when accompanied by regular contractions, dull backache or pelvic pressure
- Problems with the cervix, such as a cervical infection, inflamed cervix or growths on the cervix
- Uterine rupture, a rare but life-threatening occurrence in which the uterus tears open along the scar line from a prior C-section
Normal vaginal bleeding during pregnancy
In addition to potentially worrisome causes of bleeding, some vaginal bleeding near the end of pregnancy is normal. As the cervix begins to thin out and relax in preparation for labor, the thick plug of mucus that seals the opening of the cervix is dislodged. When this happens, you may notice a thick or stringy discharge that may be tinged with blood. This "bloody show" is a normal sign of impending labor that may occur up to a week or two before delivery.
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.
- Norwitz ER, et al. Overview of the etiology and evaluation of vaginal bleeding in pregnant women. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Garner EI. Management of hydatidiform mole. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Lockwood CJ, et al. Management of placenta previa. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Lockwood CJ. Pathogenesis of preterm birth. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Tulandi T, et al. Spontaneous abortion: Risk factors, etiology, clinical manifestations, and diagnostic evaluation. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Johnson JR, et al. Cervical insufficiency. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Ananth CV, et al. Clinical features and diagnosis of placental abruption. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Tulandi T. Clinical manifestations, diagnosis, and management of ectopic pregnancy. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Berghella V. Repeat cesarean delivery. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Chiang JW, et al. Epidemiology, clinical manifestations and diagnosis of gestational trophoblastic disease. http://www.uptodate.com/home/index.html. Accessed Feb. 10, 2009.
- Bleeding during pregnancy. American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp038.cfm. Accessed Feb. 10, 2009.
- Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 16, 2009.