An abortion is the termination of a
pregnancy by loss or destruction of the fetus before birth. An abortion may be spontaneous
or induced. The latter is an act with ethical and legal ramifications.
Medical Aspects
Spontaneous abortion, or miscarriage, occurs when the embryo fails to develop, when there is complete or incomplete expulsion of the products of conceptionÑthe embryo or fetus, and placentaÑor when the fetus dies prior to 20 weeks from the woman's last menstrual period (LMP). If fetal death occurs at 20 weeks or more after the LMP, it is termed a late fetal death or a stillbirth.
Perhaps as many as three-fourths of conceptions are spontaneously aborted. Most occur before the woman's
pregnancy can be confirmed, prior to 6 weeks after her LMP. They constitute about one-fifth of confirmed pregnancies and about one-tenth of all hospitalizations for pregnancy in the United States. The woman may experience cramping and blood loss similar to that of a normal menstrual period, heavier cramping or blood loss, or pains resembling those of childbirth.
Induced abortion is a
procedure intended to terminate a pregnancy and to produce a nonviable fetus at any gestational age. Most induced abortions in the United States are performed in the first trimesterÑwithin 12 weeks of the LMP. Virtually all first-trimester pregnancy terminations utilize a procedure called vacuum aspiration or vacuum curettage. After dilation of the cervix, a hollow plastic tube with a hole near its end is inserted into the uterus. The embryo or fetus and placenta are drawn into the tube through vacuum pressure.
Second-trimester induced abortion is more complicated. At no more than 16 weeks since the LMP, the most common technique is dilation and evacuation, a method similar to vacuum aspiration. The next most common procedure, injection of fluid containing saline solution or hormones called prostaglandins into the amniotic sac, usually is postponed until after the 16th week in order to reduce the risk of injection outside the amniotic cavity. Comparative studies of abortion techniques have determined that surgical evacuation techniques, especially up to 17 weeks' gestation, are safer than injection techniques. Hysterotomy (surgical incision of the uterus) and hysterectomy may be used when medically indicated.
In France during the 1980s an abortion-inducing drug called RU 486 was proved 85 percent effective during the first six weeks after LMP, especially when used with prostaglandins. By the mid-1990s the drug was licensed in France, China, the United Kingdom, and the United States as an abortifacient, and was in U.S. trials for use against cancer.