A miscarriage is the spontaneous loss of a fetus before the 20th week of pregnancy. (Pregnancy losses after the 20th week are called stillbirths.)
A miscarriage may also be called a "spontaneous abortion." This refers to naturally occurring events, not to medical abortions or surgical abortions.
Other terms for the early loss of pregnancy include:
- Complete abortion: All of the products (tissue) of conception leave the body.
- Incomplete abortion: Only some of the products of conception leave the body.
- Inevitable abortion: Symptoms cannot be stopped and a miscarriage will happen.
- Infected (septic) abortion: The lining of the womb (uterus) and any remaining products of conception become infected.
- Missed abortion: The pregnancy is lost and the products of conception do not leave the body.
Your health care provider may also use the term "threatened miscarriage." The symptoms of this condition are abdominal cramps with or without vaginal bleeding. They are a sign that a miscarriage may occur.
Most miscarriages are caused by chromosome problems that make it impossible for the baby to develop. Usually, these problems are not related to the mother's or father's genes.
Other possible causes of miscarriage include:
- Drug and alcohol abuse
- Exposure to environmental toxins
- Hormone problems
- Physical problems with the mother's reproductive organs
- Problem with the body's immune response
- Serious body-wide (systemic) diseases in the mother (such as uncontrolled diabetes)
Around half of all fertilized eggs die and are lost (aborted) spontaneously, usually before the woman knows she is pregnant. Among women who know they are pregnant, 15 to 20 out of every 100 will have a miscarriage. Most miscarriages occur during the first 7 weeks of pregnancy. The rate of miscarriage drops after the baby's heartbeat is detected.
The risk of miscarriage is higher in women:
- Who are older. The risk increases after age 30, becomes even greater between 35 and 40, and is highest after 40.
- Who have had previous miscarriages.
Possible symptoms include:
- Low back pain or abdominal pain that is dull, sharp, or cramping
- Tissue or clot-like material that passes from the vagina
- Vaginal bleeding, with or without abdominal cramps
Exams and Tests
During a pelvic exam, your health care provider may see that your cervix has opened (dilated) or thinned out (effacement).
Abdominal or vaginal ultrasound may be done to check the baby's development and heartbeat, and the amount of your bleeding.
The following blood tests may be performed:
- Blood type (if you have an Rh-negative blood type, you would require a treatment with Rh-immune globulin. See: Rh incompatibility)
- Complete blood count (CBC) to determine how much blood has been lost
- HCG (qualitative) to confirm pregnancy
- HCG (quantitative) done every several days or weeks
- White blood count (WBC) and differential to rule out infection
When a miscarriage occurs, the tissue passed from the vagina should be examined. This is done to determine if it was a normal placenta or a hydatidiform mole (a rare growth that forms inside the womb early in pregnancy). It is also important to determine whether any pregnancy tissue remains in the uterus.
If the pregnancy tissue does not naturally leave the body, you may be closely watched for up to 2 weeks. Surgery (suction curettage, D and C) or medicine may be needed to remove the remaining contents from your womb.
After treatment, women usually resume their normal menstrual cycle within 4 to 6 weeks. Any further vaginal bleeding should be carefully monitored. It is often possible to become pregnant immediately. It is recommended that you wait one normal menstrual cycle before trying to become pregnant again.
Complications of a complete miscarriage are rare.
An infected abortion may occur if any tissue from the placenta or fetus remains in the uterus after the miscarriage. Symptoms of an infection include fever, vaginal bleeding that does not stop, cramping, and a foul-smelling vaginal discharge. Infections can be serious and require immediate medical attention.
Women who lose a baby after 20 weeks of pregnancy receive different medical care. This is called premature delivery or fetal demise and requires immediate medical attention.
After a miscarriage, women and their partners may feel sad. This is normal. If your feelings of sadness do not go away or get worse, seek advice from family and friends as well as your health care provider.
When to Contact a Medical Professional
Call your health care provider if vaginal bleeding with or without cramping occurs during pregnancy.
Call your health care provider if you are pregnant and notice tissue or clot-like material that passes through your vagina. Collect the material and bring it to your health care provider for examination.
Early, comprehensive prenatal care is the best prevention for complications of pregnancy, such as miscarriage.
Miscarriages that are caused by systemic diseases can be prevented by detecting and treating the disease before pregnancy occurs.
Miscarriages are also less likely if you avoid things that are harmful to your pregnancy. These include x-rays, recreational drugs, alcohol, high caffeine intake, and infectious diseases.
When a mother's body has difficulty keeping a pregnancy, signs such as slight vaginal bleeding may occur. This means there is a possibility of miscarriage. But it does not mean one will definitely occur. A pregnant woman who develops any signs or symptoms of threatened miscarriage should contact her prenatal provider immediately.
Taking a prenatal vitamin or folic acid supplement before you become pregnant can greatly lower the chances of miscarriage and certain birth defects.
Abortion - spontaneous; Spontaneous abortion; Abortion - missed; Abortion - incomplete; Abortion - complete; Abortion - inevitable; Abortion - infected; Missed abortion; Incomplete abortion; Complete abortion; Inevitable abortion; Infected abortion
American College of Obstetricians and Gynecologists. ACOG Committee opinion no. 462: Moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010;116(2 Pt 1):467-8. PMID: 20664420 www.ncbi.nlm.nih.gov/pubmed/20664420.
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.
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):165-81. Reaffirmed April 2010. PMID: 15959648 www.ncbi.nlm.nih.gov/pubmed/15959648.
Simpson JL, Jauniaux ERM. Pregnancy loss. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 26.
Update Date 11/16/2014
Updated by: Cynthia D. White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.