General Fertility Rate: Number of live births / Number of women aged 15-44  

Total Fertility Rate: Sum of age specific fertility rates

Gross Reproduction Rate: Average number of daughters produced by a woman during her reproductive life time (sum of age specific fertility rates for female births). 

Net Reproduction Rates :  Average number of daughters, allowing for mortality, who survive to the age of the mother during her reproductive life time (sum of age specific fertility rates for female births of mothers minus age specific mortality rates of daughters).