The true work for a young woman is to bear and raise children. Biology mandates that she do this during her prime childbearing years, 16-32. This is so that she can raise these children with all the energy and ability of adulthood: Age 20-52.
Naturally, a woman thus wants to make babies. We should expect that the Peak Baby-Making Impulse should coincide with Peak Fertility. This is different for women than for men. A man wants to have sex. A man doesn’t know, for sure, if a child is his. But, if he has sex often enough (assuming no contraception), with fertile women, then he can be reasonably assured of having offspring. A woman knows whether she has had a child, and if the child is hers. Thus, if having sex is a man’s reproductive imperative, giving birth is a woman’s.
Today, between reliable and nearly-free contraception (especially hormonal birth control, but even the simple condom), and also readily-available abortion, and even the option of offering a baby for adoption after birth, it is hard to imagine that any woman who gives birth, and keeps the child, does so against her wishes. She wanted to have the baby. Condoms are considered a poor form of contraception. But, in Japan, where hormonal birth control was banned until just a few years ago, and for many decades condoms were the primary form of birth control, only 3% of children are born to single mothers. Birth control doesn’t work, in the US, because people don’t want it to work.
I know the daughter of a friend of mine. She is the Girl Who Loved Children. Her natural inclination, as a teen, was toward children and furry animals. She had no interest in academics and career. She was sent to college, where she milled around aimlessly. (I don’t know if she graduated.) A few years later, she was pregnant by some ne’er-do-well who soon disappeared. Now she is a mom. My friend is not quite unhappy about this. Out of three daughters, this child is his only grandchild. His eldest daughter did well in school, got a job in a big financial institution, and now makes four times his income. No grandkids, though.
Today, about 25% of children born to White women are born to unmarried mothers. We must consider this essentially voluntary. These women have children because they wanted children. And what’s wrong with that?
In the past, it was easy for women to have children, during their peak childbearing years, because it was easy to get married around Age 18-20, or at least, by Age 25.
If you don’t make it easy for women to marry, before having children, then they will have children without getting married.