To put it brutally, if that was the case, then, so what? Yeah, some kids die of preventable illness or hunger... but they're expendable in a crisis such as a famine. It's better to feed the adults and let the weak, the young, die as they tend to be the least productive with the least amount of "investment" and the longest time until they become contributors. The adults can, when things balance out, reproduce and replace lost offspring.Lord Beria3 wrote: Surely if have few resources, than having lots of children puts you at massive risk of not securing sufficient resources to feed them every year, running the risk of them starving to death.
But the reality, on the whole, even in Africa now, is that extreme famine is a once in a generation thing... normally enough children can be brought up inbetween famines to ensure that the energy expended in bringing them will be "rewarded" by them providing labour, money and or social care to the parents.
The more children you have the better your own survival in general, both short and long term.
Rather than money, either the surplus or lack of it, being the cause for high or low birth rates, many studies seem to point towards education of women being far more important. Less education for women means less control over all aspects of their lives, including birth control. It's one of the reasons the Taliban denied access to education to women and why Afghanistan (and other largely illiterate countries) have high birth rates.