An abortion is the termination of a pregnancy by the removal or expulsion from the uterus of a fetus/embryo, resulting in or caused by its death. An abortion can occur spontaneously due to complications during pregnancy or can be induced, in humans and other species. In the context of human pregnancies, an abortion induced to preserve the health of the gravida (pregnant female) is termed a therapeutic abortion, while an abortion induced for any other reason is termed an elective abortion. The term abortion most commonly refers to the induced abortion of a human pregnancy, while spontaneous abortions are usually termed miscarriages.

Abortion has a long history and has been induced by various methods including herbal abortifacients, the use of sharpened tools, physical trauma and other traditional methods. Contemporary medicine utilizes medications and surgical procedures to induce abortion. The legality, prevalence, and cultural views on abortion vary substantially around the world. In many parts of the world there is prominent and divisive public controversy over the ethical and legal issues of abortion. Abortion and abortion-related issues feature prominently in the national politics in many nations often involving the opposing pro-life and pro-choice worldwide social movements. The approximate number of abortions performed worldwide in 2003 was 42 million, which declined from nearly 46 million in 1995.Fact: date=May 2009

Spontaneous abortion

main: Miscarriage

Spontaneous abortion (also known as miscarriage) is the expulsion of an embryo or fetus due to accidental trauma or natural causes before approximately the 22nd week of gestation; the definition by gestational age varies by country. NB: This definition is subject to regional differences, see miscarriage. Most miscarriages are due to incorrect replication of chromosomes; they can also be caused by environmental factors. A pregnancy that ends before 37 weeks of gestation resulting in a live-born infant is known as a "premature birth". When a fetus dies in utero after about 22 weeks, or during delivery, it is usually termed "stillborn". Premature births and stillbirths are generally not considered to be miscarriages although usage of these terms can sometimes overlap.

Between 10% and 50% of pregnancies end in clinically apparent miscarriage, depending upon the age and health of the pregnant woman. Most miscarriages occur very early in pregnancy, in most cases, they occur so early in the pregnancy that the woman is not even aware that she was pregnant. One study testing hormones for ovulation and pregnancy found that 61.9% of conceptuses were lost prior to 12 weeks, and 91.7% of these losses occurred subclinically, without the knowledge of the once pregnant woman.