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.
Total fertility rate
Developed countries usually have a significantly lower fertility rate, often correlated with greater wealth, education, urbanization, or other factors. Mortality rates are low, birth control is understood and easily accessible, and costs are often deemed very high because of education, clothing, feeding, and social amenities. With wealth, contraception becomes affordable. In countries like Iran where contraception was subsidized before the economy accelerated, birth rate also rapidly declined. Further, longer periods of time spent getting higher education often mean women have children later in life. Female labor participation rate also has substantial negative impact on fertility, but not in all countries (for countries in the OECD, increased female labor participation has been associated with increased fertility).