Birth rate
According to the CIA's "The World Factbook", the country with the highest birth rate is Niger at 6.49 children born per woman and the country with the lowest birth rate is Taiwan, at 1.13 children born per woman.
Demographics of Bangladesh
Bangladesh has the highest population density in the world, excluding a handful of city-states and small countries with populations under 10 million, such as Malta and Hong Kong. The total fertility rate (TFR) has been reduced by more than two thirds since Independence. Current TFR in Bangladesh is 2.1 which means that women have 2.1 children on average in their lifetime. At this TFR and without migration, country's population will eventually be neither growing nor shrinking, once the top of its age pyramid fill in.
Most of the demographic statistics below are from the CIA World Factbook, unless otherwise indicated.