A measure of the fecundity of a cohort of females in a population. It can be expressed as the average number of daughters born, assuming age-specific birth rates, throughout the reproductive life of the females. The gross reproduction rate assumes that none of the cohort will die during their reproductive life, whereas the net reproduction rate accounts for the expected proportion of deaths during that time (i.e. mortality). Hence, a net reproduction rate greater than 1 means that the population will maintain or increase its size—for example, a rate of 2 would indicate a doubling of the population size within a generation. Conversely, a rate of less than 1 means the population size will decline.