Total Period Fertility Rate. Since there are differences in the number of births amongst women of different ages, one measure of fertility is the number of births per 1,000 women for a specific age-group. For example, 203 births per 1,000 women aged 25-29 years. However, this method results in different fertility estimates for each age group, and the overall fertility rate among different geographical areas cannot be easily compared. This is particularly the case, if there are differences in the age women tend to have their children among different geographical areas or countries. The TPFR is a convenient summary measure of the fertility. It is a hypothetical estimate of completed fertility. It indicates how many births a woman would have by the end of her reproductive life, if, for all of her childbearing years, she was to experience the age-specific birth rates for a given year (e.g. current fertility rates). It takes into account the differences in the fertility rates within different reproductive age groups, and enables comparisons to be made between different geographical areas and between different time periods, because it is not affected by the age distribution of the women in the reproductive age-groups. These rates are not predictions of fertility as the measures use the current rates.