difference between total fertility rate and crude birth rate
Total fertility rate The TFR (or TPFRâ€”total period fertility rate) is a better index of fertility than the crude birth rate (annual number of births per thousand population) because it is independent of the age structure of the population, but it is a poorer estimate of actual completed family size than the total cohort fertility rate, which is obtained by summing the age-specific fertility rates that actually applied to each cohort as they aged through time. In particular, the TFR does not necessarily predict how many children young women now will eventually have, as their fertility rates in years to come may change from those of older women now. However, the TFR is a reasonable summary of current fertility levels.
Human sex ratio Like most sexual species, the sex ratio in humans is approximately 1:1. Due to higher female fetal mortality,[2] the sex ratio at birth worldwide is commonly thought to be 107 boys to 100 girls,[3] although this value is subject to debate in the scientific community. The sex ratio for the entire world population is 101 males to 100 females.[4] Depending upon which definition is used, between 0.1% and 1.7% of live births are intersex.[5][6]