Net reproduction rate

The net reproduction rate (NRR) is the average number of daughters that would be born to a female (or a group of females) if she passed through her lifetime conforming to the age-specific fertility and mortality rates of a given year. This rate is similar to the gross reproduction rate but takes into account that some females will die before completing their childbearing years. An NRR of one means that each generation of mothers is having exactly enough daughters to replace themselves in the population. If the NRR is less than one, the reproductive performance of the population is below replacement level.

The NRR is particularly relevant where sex ratios at birth are significantly affected by the use of reproductive technologies, or where life expectancy is low.

The current (2010–15) estimate for the NRR worldwide under the UN's medium variant model is 1.1 daughters per woman.

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