"Miscarriage" is the lay term for the natural or accidental termination of a pregnancy at a stage where the fetus is incapable of surviving. The medical term for it is "abortion"; when the abortion is not deliberately induced, it is termed a "spontaneous abortion," so that is a synonym for "miscarriage." Miscarriages can occur for many reasons, not all of which can be identified. While miscarriage can result from physical trauma, like exposure to certain chemicals, diseases, or physical blows, they are rarely the cause. A miscarriage usually results from biological defects in the mother or genetic defects in the developing fetus.

Most such terminations occur very early in pregnancy, during the first trimester, and many people restrict the term "miscarriage" to terminations during the second trimester. Miscarriages frequently occur so early that the woman is not even aware that she is pregnant. Some women are prone to miscarry; the term "habitual abortion" describes the condition where three consecutive pregnancies have terminated before 20 weeks gestation.

If a pregnant woman has first trimester vaginal bleeding, she is said to have a "threatened abortion", and 50% of the time will proceed to miscarriage. Several symptoms indicate that a woman is about to have an "inevitable abortion", which indicates that she has an absolute probability of miscarrying. If some of the tissue remains after the fetus has died, this is called an "incomplete abortion", and if the fetus remains in the uterus, this is said to be a "missed abortion". When looking for gross or microscopic pathologic symptoms of miscarriage, one looks for the products of conception. Microscopically, these include villi, trophoblast, fetal parts, and background gestational changes in the endometrium.

In the past, a frequently used euphemism for miscarriage was to say that the mother "lost the baby". This phrase is not as popular in current times, because there is less of a cultural stigma on discussing issues related to reproduction, and because some people feel that it carries the connotation that the expectant mother was, somehow, at fault for the miscarriage.

External links

• MedLine Plus (http://www.nlm.nih.gov/medlineplus): Spontaneous Abortion (http://www.nlm.nih.gov/medlineplus/ency/article/001488.htm)
• Hormones predict miscarriage risk (http://news.bbc.co.uk/2/hi/health/3971855.stm)
• Miscarriage Overview (http://www.emedicinehealth.com/articles/12305-1.asp)

See also: childbirth, stillbirth, premature birth