In impoverished and conflict torn countries, there isn't much worse that the situation could get with kids and the mortality rate is higher, so there's less int

In impoverished and conflict torn countries, there isn't much worse that the situation could get with kids and the mortality rate is higher, so there's less interest in family planning. On top of that, most such countries are ones where there is significant cultural pressure to have children early. This also translates to other things, if people are having families in their early 20s, the third generation has relatively young grandparents. If they're having them in the late 20s, early 30s, the third generation has grandparents who are in their 60s and not as capable of chasing after toddlers all day. Being expected to give up on career goals also comes down to the same issue, when you're primarily focused on staying afloat, your career goals are also just to not have things get worse. Famine or war would not reverse this in the West, unless it was at apocalyptic levels such as to cause a total cultural reset back to a society where women are seen as child factories first.