The lead article of the International Family Planning Perspectives, March 2003 issue, sheds light on the complicated relationship between contraception and abortion, providing a valuable review of the seemingly contradictory evidence from countries with reliable information on both the issues.

The article, written by Cicely Marston and John Cleland, both from the Centre for Population Studies, London School of Hygiene & Tropical Medicine, draws from the observation that the relationship between levels of contraceptive use and the incidence of induced abortion is ambiguous. Some observers argue that the use of abortion decreases as contraceptive prevalence rises while others claim that increased use of family planning methods causes abortion incidence to rise, the paper states at the outset.

“The explanation for these counterintuitive trends is clear”, the authors explain, continuing: “In societies that have not yet entered the fertility transition, both actual fertility and desired family size are high. In such societies, couples are at little (or no) risk of unwanted pregnancies. The advent of modern contraception is associated with a destabilization of high fertility preferences. Thus, as contraceptive prevalence rises and fertility starts to fall, an increasing proportion of couples want no more children... and exposure to the risk of unintended pregnancy also increases as a result”.

“In the early and middle phases of fertility transition, adoption and sustained use of effective methods of contraception by couples who wish to postpone or limit childbearing is still far from universal. Hence the growing need for contraception may outstrip use itself; thus, the incidence of unintended pregnancies rises”.

The paper provides empirical illustrations to assess the validity of the proposed model. It also reviews trends in the incidence of abortion and contraceptive use for specific countries based on published articles, and presents a comprehensive examination of such trends in all countries thought to possess reliable trend data and in which major changes in contraceptive prevalence or effectiveness have been recorded.

The results highlighted in the article are that in seven countries (such as Kazakhstan, Kyrgyz Republic, Turkey and Uzbekistan), abortion incidence declined as prevalence of modern contraceptive use rose. In six others, including the Republic of Korea, Singapore and the United States of America, levels of abortion and contraceptive use rose simultaneously. However, after fertility levels stabilized in these latter six countries, contraceptive use continued to increase and abortion rates fell.

The conclusion reached by the authors is that: “When fertility levels in a population are changing, the relationship between contraceptive use and abortion may take a variety of forms, frequently involving a simultaneous increase in both. When other factors - such as fertility - are held constant, however, a rise in contraceptive use or effectiveness invariably leads to a decline in induced abortion”.