"Declining birth rates" tend to occur in places where women have a) education, and b) choice. If you don't know you don't have to pop out kids by the dozen until your body fails from the strain, that's just what you do. It's normal. If you live somewhere that does not allow any female identity other than wife/mother, or no social support systems for your old age other than the kindness of your kids, you may resent it or wish for more, but you make the best of what you can. I find the interesting flip side of these things in the current mega-family craze. First, there is an element of reinforcing power dynamics. But there is ALSO an element of people recognizing that societal support systems are crumbling, and they might need to depend on family in the future. So, they'd be better off with a bigger one.