You speak of circumstances which I am not familiar with.
But I can tell you that fertility of Muslim and Hindu women aren't different between Bangladesh and India. So the trope of Muslim families having more children is basically fiction.
Bangladesh fertility rate (child borne per woman) is even lower than India in most cases. And is lower than replacement rate in most areas. So overall population in Bangladesh is in decline.
In India itself - most Hindu majority areas have high fertility rates - mostly in North Indian states like UP, Bihar, MP (basically cow belt BIMARU states with low rates of education).
The second map shows Bangladesh as well which is more recent.
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View attachment 13205