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.
Girl
Child marriages, where girls are married at young ages (often forced and often to much older husbands) remain common in many parts of the world. They are fairly widespread in parts of the world, especially in Africa, South Asia, Southeast and East Asia, the Middle East, Latin America, and Oceania. The ten countries with the highest rates of child marriage are: Niger, Chad, Central African Republic, Bangladesh, Guinea, Mozambique, Mali, Burkina Faso, South Sudan, and Malawi.