In population ecology and demography, the net reproduction rate, R<sub>0</sub>, is the average number of offspring (often specifically daughters) that would be born to a female 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 R<sub>0</sub> of one means that each generation of mothers is having exactly enough daughters to replace themselves in the population. If the R<sub>0</sub> is less than one, the reproductive performance of the population is below replacement level.
The R<sub>0</sub> 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 (2015âÂÂ20) estimate for the R<sub>0</sub> worldwide under the UN's medium variant model is 1.09 daughters per woman.