A threatened miscarriage is a condition that suggests a miscarriage might take place before the 20th week of pregnancy.

A small number of pregnant women have some vaginal bleeding, with or without abdominal cramps, during the first trimester of pregnancy. When the symptoms indicate a miscarriage is possible, the condition is called a "threatened abortion." (This refers to a naturally occurring event, not medical abortions or surgical abortions.)

Miscarriage occurs in just a small percentage of women who have vaginal bleeding during pregnancy.

For more information, see: Miscarriage

Symptoms of a threatened miscarriage include:

• Abdominal cramps with or without vaginal bleeding
• Vaginal bleeding during the first 20 weeks of pregnancy (last menstrual period was less than 20 weeks ago)

Note: During an actual miscarriage, low back pain or abdominal pain (dull to sharp, constant to intermittent) typically occurs, and tissue or clot-like material may pass from the vagina.

Abdominal or vaginal ultrasound may be done to check the baby's development, heart beat, and amount of bleeding. A pelvic exam will be done to check the cervix.

The following blood tests may be performed:

• Beta HCG (quantitative) test over a period of days or weeks to confirm whether the pregnancy is continuing
• Complete blood count (CBC) to determine amount of blood loss
• Serum HCG to confirm pregnancy
• White blood count (WBC) with differential to rule out infection

You may be told to avoid or restrict some forms of activity, or you may need complete bed rest. Not having sexual intercourse is usually recommended until the warning signs have disappeared.

The use of progesterone is controversial. It might relax smooth muscles, including the muscles of the uterus. However, it also might increase the risk of an incomplete abortion or an abnormal pregnancy. Unless there is a luteal phase defect, progesterone should not be used.

Many women with threatened miscarriage go on to have a normal pregnancy.

• Anemia
• Infection
• Miscarriage
• Moderate-to-heavy blood loss

If you know you are (or are likely to be) pregnant and you have any symptoms of threatened miscarriage, contact your prenatal health care provider immediately.

Some studies show that women who get prenatal care have better pregnancy outcomes, for themselves and their babies. Early and complete prenatal care reduces the risk of miscarriage.

It is better to find and treat health problems before you get pregnant than to wait until you're already pregnant. Many miscarriages that are caused by body-wide (systemic) diseases that can be prevented by detecting and treating the disease before becoming pregnant.

Miscarriages are less likely if you receive early, comprehensive prenatal care and avoid environmental hazards such as x-rays, drugs and alcohol, high levels of caffeine, and infectious diseases.

Katz VL. Spontaneous and recurrent abortion: etiology, diagnosis, treatment. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 16.

Simpson JL, Jauniaux ERM. Pregnancy loss. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2007:chap 24.

Laurino MY, Bennett RL, Saraiya DS, et al. Genetic evaluation and counseling of couples with recurrent miscarriage: Recommendations of the National Society of Genetic Counselors. J Genet Couns. June 2005;14(3).