Demography expert Philip Longman has a superb article up at The Family in America:
Just as it is very difficult at the very top of a long market rally to persuade anyone that the bubble is about to burst, so was it nearly impossible even to contemplate in this era that the growth rate of human population would soon decline, much less go negative. As the rate of world population growth reached what we know to have been its peak in the late 1960s, biologist Paul Erlich was writing his worldwide bestseller, The Population Bomb, which predicted that the 1970s would be an apocalypse of Malthusian famine and plague.2
Meanwhile, many powerful cultural and political agendas, most notably feminism, had become attached to the conviction that overpopulation was a dire threat to humanity. In the first chapter of The Feminine Mystique, Betty Friedan had tellingly fretted about the ongoing “population explosion” before comparing the typical, highly fertile American family of the 1950s to a “comfortable concentration camp.” The link between feminism and population control had become explicit and mainstream by 1972 when President Nixon’s Commission on Population Growth and the American Future, headed by Nelson Rockefeller, recommended not only government-funded abortions, but passage of an Equal Rights Amendment to the Constitution as a means of discouraging the fertility of American women.3 Fear of over-population helped to foster a climate of opinion in which the decoupling of sex from reproduction seemed not only personally desirable, but also socially useful, thereby legitimizing a revolt against the pro-natal norms of “patriarchy.”
Well worth reading the entire piece and following up on its footnotes.