Maybe it's because the abortion rights supporters of the previous generations aborted the children they would have taught to support abortion.
In an old book free on line, Grand Illusions by George Grant, you can find other candid bad news. Dumpster divers at PP SW Texas Houston found all their patient records and were able to tell news about PP’ s fundamental mission failure the Alan Guttmacher Institute won’t admit: Though PP was founded to keep down numbers of minority women having kids, it backfired. A high proportion of their clients are white, thus adding impetus to Teddy Roosevelt’s 1906 declaration that white college educated women having 1 child per 10 graduates were committing “race suicide”.