Definition

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

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Alternative Names

Threatened miscarriage; Threatened spontaneous abortion; Abortion - threatened; Threatened abortion

Causes, incidence, and risk factors

Some pregnant women have some vaginal bleeding, with or without abdominal cramps, during the first three months 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 about half of pregnancies that have first trimester bleeding.

Symptoms

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) can occur. Tissue or clot-like material may pass from the vagina.

Signs and tests

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
• Pregnancy test to confirm pregnancy
• Progesterone level
• White blood count (WBC) with differential to rule out infection

Treatment

You may be told to avoid or restrict some forms of activity. 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. Your doctor can tell you more about this.

Expectations (prognosis)

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

Complications

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

Calling your health care provider

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 right away.

Prevention

Women who get prenatal care have better pregnancy outcomes for themselves and their babies. Miscarriages are less likely when you receive early prenatal care. And a healthy pregnancy is more likely when you avoid things that are hamful to your pregnancy such as x-rays, recreational drugs, alcohol, high caffeine intake, and infectious diseases.

It is better to treat health problems before you get pregnant than to wait until you are already pregnant. Miscarriages that are caused by body-wide (systemic) diseases can be prevented by detecting and treating the disease before becoming pregnant. Being obese or having uncontrolled diabetes can increase your risk of miscarriage.

References

Katz VL. Spontaneous and recurrent abortion: etiology, diagnosis, treatment. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 16.

American College of Obstetricians and Gynecologists. ACOG Committee opinion no. 462: Moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010 Aug;116(2 Pt 1):467-8.

Cunnigham FG, Leveno KL, Bloom SL, et al. Abortion. In: Cunnigham FG, Leveno KL, Bloom SL, et al, eds. Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010:chap 9.

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