Period Parity Progression Ratios and Birth Intervals in England and Wales, 1941-1971: A Synthetic Life Table Analysis

A method is presented for analysing maternity history data to provide period estimates of parity progression ratios, birth intervals and related indices. This is applied to a sample of the marriage and maternity histories from the Census of England and Wales of 1971 and shows: (a) a general increase through the 1950s and into the 1960s in period estimates of marriage and parity progression ratios, especially in the progression from first to second birth; (b) a general acceleration of fertility with, again, the second birth interval becoming particularly short and compact; and (c) very steep declines in third and fourth birth progression ratios from the mid-1960s. Birth interval distributions altered during the period examined. Decomposition of a progression-based total fertility index shows change in the ratios for lower birth orders to have dominated the fertility upswing and declines in ratios for higher birth orders to have initiated the subsequent decline.