Trends In Partnership Behaviour in Japan

Trends In Partnership Behaviour in Japan From The Cohort Perspective
Conference Paper from the National Institute of Population and Social Security Research, Japan

Assumptions about the future age-specific fertility rates required for population projections can be obtained using the cohort fertility method. With this method, we predict the average completed family size of younger cohorts, based on the actual birth process of preceding cohorts. Since childbearing behaviour is affected by family formation and dissolution, it is essential to examine these processes for constructing and assessing the future fertility assumptions. Results we will show in this paper are based on the preliminary analyses for producing official population projections for Japan conducted by the National Institute of Population and Social Security Research (NIPSSR).

In this paper, we describe patterns of partnership formation and dissolution from the birth cohort perspective. Recognizing that declining exposure to marriage may place a strong structural restriction on childbearing, we then examine the extent to which these behavioural changes contribute to a fertility decline by cohort. In addition to marriage, divorce, bereavement and remarriage may also be significant factors for fertility.



Fertility assumptions for new population projections for Japan based on the 2005 census extremely low – in 2030, the medium variant TFR for Japanese women is assumed to be These prospects were led by drastic changes in the patterns of family formation and dissolution. Among the 1990 birth cohort, the mean age at first marriage is 28.2, the proportion never-married women at age 50 extends to 23.5%, and 36% of first-married women eventually experience divorce.

Counterfactual CTFRs with variant patterns of family formation and dissolution have allowed us to understand that over 70% of the CTFR decline is attributed to a decline in marriage rates, and if divorce behaviour has not changed since the 1955 birth cohort, CTFR will by 3% in the 1990 birth cohort.

Developed countries with relatively high fertility rates show relatively high levels of unmarried couples cohabiting and bearing children among the youth. The visibility of cohabitation and childbearing of unmarried couples is still low in Japan, but among the 1980s later birth cohorts, these new patterns of family formation have been increasing. Since these changes could lead to a rise in fertility rates for women in their 20s in the near future, we need to attention to these trends.