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 Singapore
After World War II, in the period from 1947 to 1957, Singapore saw a massive population increase mostly due to increased number of native births. The birth rate rose and the death rate fell; the average annual growth rate was 4.4%, of which 1% was due to immigration; Singapore experienced its highest birth rate in 1957 at 42.7 per thousand individuals. (This was also the same year the United States saw its peak birth rate.)