Diminishing population growth rates in poor countries can be partially attributed to

Maybe right depends on the subject but a major study shows that poor countries have higher birthrates but in first world countries there is less thats is why there is less babies being born in the 1st world countries because of the better health care and access to cleaner water and more food and economic growth and lesser corruption so the awnser would be economic growth or you can rephrase the words i used to make an awser that fits hopefully i helped

Ithink the answer is baby boomers ?