Another significant reason people forget is AIDS. Until then, about mid-80’s, “social diseases” were something that happened to “other people” lower on the social scale and were curable with antibiotics. Protection was a stigma particularly for teens, that they planned to have sex instead of calling it spontaneous. Suddenly, society seemed to be flooded with a disease that was not obvious, was everywhere, and could kill you. Unlike today, people reacted by being wary of disease-inducing activity.
Abortion was an instance in a number of books back in the early 60s- I recall it was a point in Apprenticeship of Duddy Kravitz that his brother was kicked out of med school for doing one for a friend’s girlfriend; also recall a secret abortion as a plot point in some Taylor Caldwell novel. Illegal abortions happened, and the better off could also travel.
I suspect the spike in the 60’s was due to loosening morals; but a fellow I knew who grew up in the early 50’s mentioned that a lot of girls simply took a year off school to “stay with their aunt in the country” so teen pregnancies were common - just by the 60’s it was easier to find someone who could take care of it.
Also, one impetus to relax and remove Canada’s abortion laws came about because by the late 60’s some hospital medical boards were willing to give a generous interpretation to “health of the mother”. Some allowed for claims of mental health problems from being forced to carry to term, so a number of hospitals would rubber-stamp any request. I assume things were not much different in some states where a health “endangerment” clause was part of the law.