(Spontaneous Abortion)

Miscarriage Summary
A miscarriage is any pregnancy that ends spontaneously before the fetus can survive. Miscarriage usually occurs before the 13th week of pregnancy. The cause of a miscarriage cannot always be determined. The most common causes of a miscarriage in the first trimester are collagen vascular disease (lupus), hormonal problems, diabetes, chromosomal abnormalities, and congenital abnormalities of the uterus.
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Miscarriage facts

  • Spontaneous miscarriage is the loss of a pregnancy that ends spontaneously before the fetus can survive.
  • Exercise, working, and intercourse do NOT increase risk of miscarriage for women without underlying specific medical conditions that place them at risk.
  • Causes for miscarriage include genetic abnormalities, infection, medications, hormonal effects, structural abnormality of the uterus, and immune abnormalities.
  • After an isolated miscarriage, the probability of having a normal term pregnancy in the future is high.
  • Treatment of recurrent miscarriage is directed toward the underlying cause.

What is a miscarriage?

A miscarriage is any pregnancy that ends spontaneously before the fetus can survive. A miscarriage is medically referred to as a spontaneous abortion. The World Health Organization defines this unsurvivable state as an embryo or fetus weighing 500 grams or less, which typically corresponds to a fetal age (gestational age) of 20 to 22 weeks or less. Miscarriage occurs in about 8% to 20% of all recognized pregnancies, and usually occurs before the 13th week ofpregnancy. With the development of highly sensitive assays for hCG levels that can detect an early pregnancy even prior to the expected next period (menstruation), researchers have been able to show that around half of all pregnancies (recognized and unrecognized) are lost. Because the loss occurs so early, many miscarriages occur without the woman ever having known she was pregnant. Of those miscarriages that occur before the eighth week, a portion have no fetus associated with the sac or placenta. This condition is called blighted ovum, and many women are surprised to learn that there was never an embryo inside the sac.

Chances of miscarriage decrease significantly once fetal heart function is detected in a given pregnancy.

A woman who may be showing the signs of a possible miscarriage (such as vaginal bleeding) may have her pregnancy referred to as a "threatened abortion."

Medically Reviewed by a Doctor on 3/7/2014

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