PIP: This article reviews the incidence of abortion and some of the factors that contribute to differences in the use of abortion between countries and between different population groups within the same country. Liberalization of abortion started in Europe in the 1930s and continues today. Currently, some 63% of the world's people live in countries where abortion is available on request or where social factors can be taken into consideration when evaluating a woman's request for pregnancy termination. However, governments that have legalized pregnancy termination have yet to provide adequate services to meet the demand. Every year up to 53 million women seek termination of an unwanted pregnancy; between 150,000 and 200,000 women die in the process and countless more are injured for life. Factors that affect abortion rate include the concept of liberalization of abortion, sex education, and accessible family planning services and emergency contraception. Although the Netherlands permits abortion, it has the lowest reported abortion rate in the world. In the US and in Scandinavia, young unmarried women make up the largest proportion of those who obtain abortion. In most other developed countries, married women with children constitute the largest group of abortion users.