Having children is an afterthought for many women. Even getting married takes a second place to furthering their careers.
Immigration has been seen by some as the answer to this, but we have changed the system to promote whole families immigrating, which only temporarily helps the problem as the first generation of immigrants usually has more children than the rest of us, but they soon catch up with us in ensuing generations.
We try to make women into soldiers, and so we lower the standards to let more women into these roles. Is that wise? We insist that women spend years pursuing high levels of education and essentially force them to continue working at some high demand job instead of spending time with their children. We make it sound so demeaning for them to do so and so sexist to think they should.