On the tempo of childbearing in England and Wales.

Abstract The paper describes a computerized model developed to simulate the fertility of a hypothetical marriage cohort in a closed population. The model was applied to England and Wales fertility data of marriage cohorts of the years 1951 to 1970. For each of these cohorts, the computer was programmed to construct five series of tables showing birth-order probabilities, family size frequency distribution, mean length of intervals between marriage and successive births, parity progression ratios and mean family sizes of fertile women. The results showed that the fertility of the cohorts of women who married between the middle 1950s and the early 1960s was character ized by a declining trend in the frequency of childlessness and by a dramatic increase in the proportion of marriages with two or more children. Since 1964 or so, there has been a downward trend in duration-specific birth-order probabilities. The analysis suggests that the recent drop in fertility may well prove to be the effect of an upward shift in the timing of births as well as a fall in completed fertility.