Originally Posted by
atomic sagebrush
This is a bit hard to explain but no, it doesn't quite work like that. Firstly because even in poor countries, even in times of famine, there are plenty of people who are still well off, still eating enough to get and stay pregnant.
Additionally, as people become TRULY poor and impoverished, they stop ovulating (and we see that on here where people who are doing LE Diet even just a little too strictly, see their ovulation stop and are unable to get pregnant even if they are still ovulating, when their weight gets too low.) So people who might have had girls, stop getting pregnant at all. Fewer people overall might get pregnant in that type of situation but those that do are likely the ones in the best condition with the most food coming in.
So, the people who end up getting pregnant (either by choice - because who voluntarily chooses to get pregnant in a time of famine, only people who have at least a fairly adequate food supply would do that, or circumstance - they haven't stopped ovulating and are still able to conceive) are likely coming in more set for boys to begin with and this neat little mechanism seems to hold the gender ratio at about 50-50.
We do see in the nations around the equator, many of which are poor, a higher ratio of girls to boys conceived than is statistically expected. But it's only by a couple % points and not the drastic shift that you are thinking of.