Total fertility rate refers to the average number of children that would be born alive to 1 000 women during their lifetime if they were to pass through their childbearing ages 15 - 49 experiencing the age specific fertility rates prevailing in a given year 某年的总和生育率是指一千名妇女，若她们在生育龄期(即十五至四十九岁)经历了一如该年的年龄组别生育率，其一生中活产子女的平均数目。
