Twenty-three is a brilliant age to have a child, biologically. The only reason it seems young is because of the ridiculousness that society has become. We are supposed to go to university, then have a career, THEN squeeze in babies in a narrow window until we get too old, and the reason that most people can't have them right after education is because of: 1) The crazy cost of housing 2) The crazy cost of education 3) the cost of living and 4) The fact that men don't want to settle down young, they want to shag everything in sight and are encouraged in this by our over-sexualised and permissive society, where casual sex is celebrated, divorce rates are high, porn is freely available, and commitment is under-valued.
When my parents married in 1967, they could buy a family house with three double bedrooms, two bathrooms, and a large kitchen and living room for five thousand pounds. And, relative to the salaries of the time, a couple aged 24 and 27 could handle that mortgage on one average salary. And there was not a widespread requirement to spend years and tens of thousands on a university education. People trained on the job. Lawyers trained on the job, for example.
If, today, houses were much cheaper and there were more routes to well-paying jobs than just uni, and men valued commitment more, you would soon see everyone having babies in their early twenties again.
It's natural for women to pair off and want marriage and babies in their early twenties. (Obviously, not everyone wants this!) But the way society is has socialised people out of following their natural urges, for the reasons above. I think it's totally wrong and that the entire social system by which we have babies needs a complete re-think. It's just no good the way we have it now, with many women having to wait so long that they have this small window, so they end up with fewer children than they wanted, and many can't do it at all. While many are still OK to have babies later, many also are not.
If people have found a good relationship young, I think society should organise itself so that women can have babies in their late tweens and early twenties, THEN get an education. Or, have babies right after uni. You could end up having done both education/training and having your completed family, all of whom have started school, by the time you are 30-ish and THEN start your career.
It should be normal for women who want a family to start their career at 30-32, basically, instead of this expectation that women spend their twenties - their absolutely prime baby-making years - building a career. The government could offer incentives to make this happen, like introducing rent control for young families, and maybe discounted uni fees if you go after having kids, and free childcare while you're at class.
When it comes to women and biology, the current set-up is completely wrong, imo.