A spontaneous abortion, or miscarriage, is a natural termination of a pregnancy before the time that the fetus can live on its own. Approximately 10% of all diagnosed pregnancies end in miscarriage, and 20% to 40% of pregnancies end before a pregnancy diagnosis is made. Miscarriages can also occur during the second and third trimesters of pregnancy, although the percentage drops dramatically after the first trimester. A miscarriage can be very difficult emotionally for both the woman and her partner, although research has found that men experience less intense emotional symptoms for a shorter period of time (Abboud & Liamputtong, 2003).
In a significant number of miscarriages, there is some chromosomal abnormality (Christiansen, 1996), which is more common in older women (Bulletti et al., 1996). The body somehow knows that there is a problem in the developing fetus and rejects it. In other cases, in which there are no chromosomal problems, the uterus may be too small, too weak, or abnormally shaped, or the miscarriage may be caused by maternal stress, nutritional deficiencies, excessive vitamin A, drug exposure, or pelvic infection.
Symptoms of miscarriage include vaginal bleeding, cramps, and lower back pain. Usually a normal menstrual period returns within 3 months after a miscarriage, and future pregnancies may be perfectly normal. However, some women experience continual spontaneous abortions, often due to anatomic, endocrine, hormonal, genetic, and/or chromosomal abnormalities (Bick et al., 1998), and problems with defective sperm (Carrell et al., 2003). Tests are being developed to try to predict when a spontaneous abortion will occur.