I'm not sure that's necessarily the case anymore. Increasing numbers of women around the world, not just in North America and Europe, don't get married because they want to develop a career. If they get pregnant they may be unable to get paid maternity leave, and/or be discriminated against on their return to the office.
Women are women, motivated by biological instinct; females enter high paying high stress competitive sectors in the hopes of landing a high earning man, not because they genuinely want to work 80+ hour work weeks, enslaved by their phones. Look at the high turnover in high pressure jobs at places like Goldman Sachs or in other fields like law and medicine, where females drop out of the workforce to become wives and mothers and only re-enter once the children are grown up. And in many cases, these females tend not to return to the workforce if they don't have to.
Have you ever worked in any workplace ever? In my experience it tends to be women trying to get out of doing the hard yards and basically waiting around to get married. Their dream is to be a Lady of Leisure, brunching with their friends at the local cafe before picking the kids up from Daycare. I shit you not, females of the anglosphere don't even parent anymore. I once dated a New York girl from the New England area and she'd been medicated since primary school. The anglo corporate culture- whilst conducive to profits and maximising shareholder return- is completely toxic to families.
Really if you want to encourage more women to have children you need to have tough anti-discrimination policies such that they can feel confident maternity leave won't screw them over later. Second, you need more paid maternity and indeed paternity leave. In the 21st century there's no reason for men not to share more of the housework and child rearing. It's also good for the children to have more direct contact with their father growing up.
The problem is that you're projecting western ideals into how a woman should behave, as opposed to how women do behave.
Females are by nature hypergamous- they want to marry the top high earning achievers, the alpha males; in China, this translates to
高富帅 "GaoFuShuai": Tall, rich and handsome.
In a society as competitive as China, this means that once aspiring middle class chinese families send their daughters to uni, these daughters are automatically not going to date, let alone marry anyone who isn't of the same socio-economic class to attain tertiary education, and the higher paying incomes that result from such certification.
The solution is to encourage younger family formation, where the eggs are most healthy and most plentiful; female high school graduates should be encouraged to become mothers first before thinking about an education- for these females, this necessarily means not going into uni until they're about 33-35 as opposed to the current situation of shengnu, leftover females who are 33-35, university educated and don't even have kids, let alone married!