Legal & readily accessible abortion is estimated to have caused a 34 pct reduction in first births, a 19 pct reduction in first marriages, & a 63 pct reduction in "shotgun marriages" prior to age 19

The Power of Abortion Policy: Reexamining the Effects of Young Women’s Access to Reproductive Control. Caitlin Knowles Myers. Journal of Political Economy, http://www.journals.uchicago.edu/doi/pdfplus/10.1086/694293

Abstract: I provide new evidence on the relative “powers” of contraception and abortion policy in effecting the dramatic social transformations of the 1960s and 1970s. Trends in sexual behavior suggest that young women’s increased access to the birth control pill fueled the sexual revolution, but neither these trends nor difference-in-difference estimates support the view that this also led to substantial changes in family formation. Rather, the estimates robustly suggest that it was liberalized access to abortion that allowed large numbers of women to delay marriage and motherhood.

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[...] policy environments in which abortion has legal and readily accessible by young women are estimated to have caused a 34 percent reduction in first births, a 19 percent reduction in first marriages, and a 63 percent reduction in "shotgun marriages" prior to age 19.

[...]

Between the 1950 and 1955 birth cohorts, the fraction of women having sex prior to age 18 increased from 34 to 47 percent.

[...] cohorts that experienced the most rapid changes in sexual behavior exhibited little change in fertility.

[...]

Lahey (2014)...finds that the introduction of abortion restrictions in the nineteenth century increased birthrates by 4-12 percent...