Is abortion less of an issue simply because there are less abortions?

[Ban my account ffs!]

Be careful interpreting that graph.  The number of women aged 15 to 44 increased dramatically during the 1970s. The rate of increase then declined beginning in the early 1980s but continued to increase in absolute terms until the early 1990s. Then the number leveled off and has since grown very slowly.

The number of women in peak abortion years (teens and 20s) rose rapidly in the 70s but shrank after the early 80s... So the rate of abortions decreased some because the proportion of younger women in the 15-44 group declined while the more-likely-to-be-married and settled portion of 30 somethings grew.

This explains why overall pregnancies ceased growing even while births increased, peaking in 1990.  At that time, the most numerous age group of American women were between 27 and 33 years old, an age associated in modern times with starting families.

These tempo effects are not taken into account in that graph.  Also remember the age of the average child bearing mother has increased in an unprecedented manner beginning in the 1960s with the advent of the pill and has progressed since.

So the high rates of abortion around 1980 were caused by there being a huge number of younger women with a much smaller cohort of older child bearing age women.

Because of this the effective rate of abortions more or less plateaued during the 80s and the first real falls in the rate of abortions then occurred only after 1990.

There are artifacts as well... Teen pregnancies showed an unusual rise beginning around 1988 and peaking in 1990 before continuing long term slide downwards.  I'd be interested in finding a reason for this.  This blip mainly impacted girls born from 1970-1975.  

Overall, though, baby boomer women had the most abortions on average and as Gen X women moved into motherhood, abortion rates and overall numbers fell.  Keep in mind baby boomers were coming of age during Roe v Wade.