Almost half the married women of the United States have had a miscarriage before they are thirty-five years of age. Estimates indicate one abortion to every two and one half childbirths in cities and one in five in rural areas.

Abortions occur most frequently in the eighth to the twelfth week of pregnancy. "Immature labor" is interruption of pregnancy from the sixteenth to the twenty-eighth week; "premature labor" is interruption from then to the thirty-seventh week.

Spontaneous abortion occurs from any cause that brings about death of the unborn child. Infection, high fever, or asphyxiation of the mother may induce abortion. Syphilis, malformations, or injuries may stimulate expulsion of the fetus. Changes in the action of the glands and wrong nutrition may have this effect.

The chief signs of a threatened spontaneous abortion are pain in the womb or uterus; bleeding; and expulsion of all or parts of the unborn child from the mother's organs. Severe pain and bleeding of a pregnant woman should be considered a threatening sign. She should go to bed immediately; the physician should be secured as soon as possible.