The transition of reproductive life course in Japan; the lexis-layer decomposition analysis of fertility decline

Ryuichi Kaneko, National Institute of Population and Social Security Research, Tokyo

In this study, I examined the historical developments of the life course transformation of Japanese female cohorts in relation to the recent fertility decline that marks a new phase of human life. In this course, I sorted out statistical information from the vital statistics and a series of national representative surveys to reconstruct the cohort reproductive life courses on the Lexis surface and also to decompose it by marital status, parity and socioeconomic factors such as educational attainment. Those that are decomposed form strata on the Lexis surface, which I call the Lexis layer. More specifically, fertility rate is represented as a sum of the probabilities of having child by birth order, and each of the probability is composed of some structural and behavioral factors such as marriage and education. The decompositions of the probabilities are performed by the logistic regression technique, and all of those probabilities are to be observed amongst the age and time space to understand what have been happening to the women’s life courses. The study revealed detailed process of onset and evolution of marriage changes and marital fertility reduction. In other words, when, who, which birth order, and how much the Japanese female life courses have transformed are identified. I also briefly discussed about universality of the process among other societies.