The number of live-born children borne by women of a particular age group in a given period related to the average number of women in that age group and period.

Fitting curves to age-specific fertility rates: some examples. Statistical Review of the Swedish ... “Variance effects in the Bongaarts-Feeney formula.”, Demography, 38, 1: 1-16. Kohler, H-P., Ortega, ...