Abortion is the spontaneous or induced (therapeutic) expulsion of the products of conception from the uterus before 20 weeks gestation (fetal weight less than 500 g [17½2 oz]). Up to 15% of all pregnancies and about 30% of all first pregnancies end in spontaneous abortion (miscarriage). At least 75% of miscarriages occur during the first trimester.Causes
Spontaneous abortion may result from fetal, placental, or maternal factors. (See Types of spontaneous abortion.) Fetal factors usually cause abortions before the 12th week of gestation and include:
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defective embryologic development resulting from abnormal chromosome division (most common cause of fetal death)
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faulty implantation of the fertilized ovum
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failure of the endometrium to accept the fertilized ovum.
Placental factors usually cause abortion around the 14th week of gestation, when the placenta takes over the hormone production necessary to maintain the pregnancy. These factors include:
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premature separation of the normally implanted placenta
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abnormal placental implantation.
Maternal factors usually cause abortion during the second trimester and include:
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maternal infection, severe malnutrition, and abnormalities of the reproductive organs (especially an incompetent cervix, in which the cervix dilates painlessly and bloodlessly in the second trimester)
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endocrine problems, such as thyroid dysfunction or a luteal phase defect
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trauma, including any surgery that requires manipulation of the pelvic organs
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phospholipid antibody disorder
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blood group incompatibility
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drug ingestion.
The goal of therapeutic abortion is to preserve the mother’s mental or physical health in cases of rape, unplanned pregnancy, or medical conditions, such as moderate or severe cardiac dysfunction.
Signs and symptoms
Prodromal signs of spontaneous abortion include a pink discharge for several days or a scant brown discharge for several weeks before the onset of cramps and increased vaginal bleeding. For a few Continue reading »


