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Miscarriage

A miscarriage is the spontaneous loss of a fetus before the 20th week of pregnancy (pregnancy losses after the 20th week are called stillbirths). Miscarriage is a naturally occurring event, unlike medical or surgical abortions.

A miscarriage may also be called a "spontaneous abortion." 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.

Causes

Most miscarriages are caused by chromosome problems that make it impossible for the baby to develop. In rare cases, these problems are related to the mother's or father's genes.

Other possible causes of miscarriage may include:

  • Drug and alcohol abuse
  • Exposure to environmental toxins
  • Hormone problems
  • Infection
  • Overweight
  • 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)
  • Smoking

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, about 10% to 25% 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 30 years of age and becomes even greater between 35 and 40 years, and is highest after age 40.
  • In women who have already had several miscarriages.