Sklar J, Berkov B
Science. 1974 Sep 13;185(4155):909-15. doi: 10.1126/science.185.4155.909.
In sum, it appears that legal abortion depressed overall fertility, but particularly illegitimate fertility, by giving women an opportunity to terminate their pregnancies when other means of birth control either had not been used or had failed. If legalized abortion had not been available, an estimated additional 39,000 illegitimate babies and 28,000 legitimate babies would have been born in 1971 in the United States. While this makes up a small part of total births (3,500,000), the illegitimate births prevented represent almost onetenth of all out-of-wedlock children born in the country in that year. In addition to preventing these births the legalization of abortion appears to have reduced the incidence of pregnancy-related marriages and thereby may have helped to limit subsequent marital disruption. Finally, legal abortion prevented large numbers of illegal abortions from occurring. Our data indicate that well over half-most likely between two-thirds and three-fourths-of all legal abortions in the United States in 1971 were replacements for illegal abortions. Further declines in illegitimate birth rates for the country as a whole will depend, in considerable part, on the extent to which legal abortion becomes more readily available and more widely used. Theoretically, greater use of efficient contraception could also cause illegitimate fertility to decline. But there are many reasons why women do not use efficient contraception even when they know about it and have access to the materials (25). Even though the use of abortion throughout the nation is now legalized by the Supreme Court decision, this does not necessarily mean that services will in fact be everywhere more readily available. Our interstate analysis suggests that should the liberalization of abortion laws be reversed, not only would there be an upturn in illegal abortions and pregnancy-related marriages, but also a marked rise in illegitimacy, particularly among women who do not have the means to obtain an illegal abortion.
总之，合法堕胎似乎降低了总体生育率，尤其是非婚生育率，因为它让女性在其他避孕方法未被采用或失败时，有机会终止妊娠。如果没有合法堕胎，据估计1971年美国会多出生约3.9万非婚婴儿和2.8万婚生婴儿。虽然这在总出生数（350万）中占比很小，但被避免的非婚出生数几乎占该年美国所有非婚生子女的十分之一。除了避免这些出生，堕胎合法化似乎还降低了与怀孕相关的婚姻发生率，从而可能有助于减少随后的婚姻破裂。最后，合法堕胎防止了大量非法堕胎的发生。我们的数据表明，1971年美国超过半数——很可能在三分之二到四分之三之间——的合法堕胎是对非法堕胎的替代。整个国家非婚生育率的进一步下降在很大程度上取决于合法堕胎变得更容易获得和更广泛使用的程度。从理论上讲，更多地使用高效避孕措施也可能导致非婚生育率下降。但即使女性了解并能获得高效避孕措施，她们不使用的原因也有很多。尽管最高法院的裁决使全国范围内堕胎合法化，但这并不一定意味着各地的堕胎服务实际上会更容易获得。我们的州际分析表明，如果堕胎法的自由化被逆转，不仅非法堕胎和与怀孕相关的婚姻会增加，非婚生子女率也会显著上升，尤其是在那些没有办法进行非法堕胎的女性中。
