Unintended pregnancies in the United States, 1970--1972.
There were about 2.0--2.3 million unintended pregnancies in the United States each year during the early 1970s. Within this framework, the rapid rise in the number of abortions since 1973, to 1.3 million in 1977, is quite predictable.
D000024:Abortion, Illegal; D000029:Abortion, Legal; D003267:Contraception; D005260:Female; D006801:Humans; D011247:Pregnancy; D011275:Pregnancy, Unwanted; D014481:United States