§ Mr. Moyle,
pursuant to his reply [Official Report, 26th October 1977 ; Vol. 936, c. 759], gave the following information
Two possible measures of the average size of the family in England and Wales, the period fertility rate and a cohort fertility rate, are given below. The period rate is the average number of live born children per woman that would result if women were subject over their reproductive ages to the age-specific fertility rates—live births per woman in each age group—of the year in question. Actual figures of completed family size, reflecting the whole child-bearing experience can be given only for women who have reached.piddle-age. The period fertility rate is more volatile than the cohort rate.
Calendar yearActual Total periodfertility ratein the year Average numberof live bornchildren towomen reachingage 45 inthe year Actual (a) (b) 1940 1.74 2.15 1950 2.18 1.80 1955 2.22 1.80 1960 2.66 1.91 1965 2.86 2.00 1970 2.41 2.12 1975 1.79 2.34 Assumptions 1980 1.65 2.42 1985 2.06 2.38 1990 2.10 2.19 1995 2.10 1.93 2000 2.10 1.82
The assumptions for future fertility shown in column (a) are annual figures incorporated in the 1976-based official population projections ; the figures in column (b) for 1980 and 1985 largely reflect the actual child-bearing experience of those women now aged 41 or 36 years respectively, but from 1990 onwards they increasingly reflect assumptions about future fertility summarised in column (a).