The effect of legalization of abortion on population growth and public health.(Statistical Data Included)

In what ways has increased access to legal induced abortion changed behavior; and what has been the impact, if any, of such changes on population growth and public health? We will attempt in this article to evaluate these phenomena, focusing on developed societies such as the United States. It is not only possible but appropriate to implement intentions as to the number and spacing of children in such societies, where contraception and legal or illegal abortion have long been used to prevent some unplanned pregnancies and births.

In all societies, legalization of abortion produces changes in the numbers of pregnancies that occur, and in the proportion terminated by legal and illegal abortion and by live births.

Other things being equal, one would expect a decline in the number of illegal abortions, because at least some women who would have sought illegal abortions may obtain them legally. This substitution would not necessarily be immediate nor would it entirely eliminate illegal abortions, as evidenced by information from such countries as Hungary, where some illegal abortions still occur even though legal abortion on request has been available and widely employed since the mid-1950s. The extent to which illegal terminations of pregnancy are replaced by legal ones is related to the nature of the new law and to its implementation by the health services, involving social and financial costs to the woman seeking abortion, issues of privacy and dignity, and public awareness of the availability of legal abortion services.

One would also expect a decline in the number of births, because at least some women who would have been deterred from seeking illegal abortions would want to terminate their pregnancies by abortion if it is legal. This decline in births depends on the number of unintended pregnancies that occurred before legalization and the degree to which abortion remains unacceptable to some women even after it has been legalized.

To the extent that unintended births are replaced by legal abortions, the total number of legal and illegal induced abortions increases subsequent to legalization. However, because of the decline in illegal abortions, the increment in the total number of induced abortions must be smaller, absolutely and relatively, than the increment in the number of legal abortions.

Because a higher incidence of abortion enables more women to return to the fecundable state sooner than if they had chosen to carry their pregnancies to term, more than one abortion is required to replace one birth. Thus, the total number of pregnancies tends to increase, even if no changes occur in the proportion of fecund women who are sexually active; in coital frequency; in contraceptive practice; and/or in contraceptive effectiveness.

The question of whether or not the legalization of abortion is likely to result in a replacement of contraception by abortion has generated some concern. In the author's view, the contention that this has happened on a grand scale is not supported by available evidence. In any event, the substitution of abortion for contraception (or an increase in sexual activity), if such were the case, would increase the numbers of abortions and, thus, of pregnancies, but it would not affect the number of births.