The message feminists put out starting in the 60s-70s that women should pursue a career first and finding a marriage partner second - and its uptake by lots of American women - has greatly exacerbated the decline in the birth rate.
Since more women than men now pursue higher education, that means there will be fewer men earning higher salaries. Most women naturally want the man to earn at least as much as they do if not more for reasons of status. Women are far more status conscious than men are.
Conversely, men strongly prefer younger women. Again, this is natural and is not going to ever change. Thus a college educated 30 something woman is not going to be anywhere near as attractive to most men as a similarly attractive woman who is 10 years younger.
Neither sex is willing to budge on those two issues. The result is a standoff and no marriage and no kids. If we want to reverse the declining birth rate we need to encourage couples to get married earlier and not put it off til later.
Marriage is nowhere near as stable as it was 50, even 30 years ago.
Women fear putting aside a career and earnings to instead invest themselves in child rearing, only to have the man leave them for a younger model and leave them in the lurch.
And statistically those fears are very valid. I for one and quite relieved that my daughters got educations and careers before they got married. If God forbid their marriages fall apart they’ll still be able to support themselves.