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.
Irish Free State
According to one report, in 1924, shortly after the Irish Free State's establishment, the new dominion had the "lowest birth-rate in the world". The report noted that amongst countries for which statistics were available (Ceylon, Chile, Japan, Spain, South Africa, Netherlands, Canada, Germany, Australia, United States, Britain, New Zealand, Finland and the Irish Free State). Ceylon had the highest birth rate at 40.8 per 1,000 while the Irish Free State had a birth rate of just 18.6 per 1,000.