Parity patterns of birth interval distribution.

A simplified model is presented for the measurement of inter-live birth interval distributions. Comparative analyses of "effective fecundability," the mean length and variation of postpartum infecundity, and the parity progression ratio based on this measurement model are presented using data from U.S. marriage cohorts and from an Indian sample. Parity differentials in these reproduction parameters are investigated, and the ramifications for fertility estimate and projection discussed.