关键词: 平均生育年龄, 孩次结构, 生育推迟, 低生育水平, 中日韩人口

Abstract: Using fertility data from national authorities and national censuses of China，Japan，and South Korea，this study analyzes the levels and trends of mean age at childbearing ( MAC) of the three countries from 1990 to 2015. After isolating the effects of parity composition and childbearing schedule respectively by decomposition technique，the article examines quantitatively the mechanism that underlies dynamic changes and cross-national differences of MACs. Results indicate that the MAC of China experienced a decrease between 1990 and 1995，followed by a sustaining growth afterwards. The increase of MAC in China is driven by the postponement of childbearing and the changes of parity composition， with the former playing a larger role. The inherent mechanism since 2010 deserves special attention. Compared with Japan and Korea，China still has relatively lower overall and parity-specific MACs. Although all of the three countries have witnessed an increase of MAC during the past 25 years， they demonstrate different patterns in terms of the roles of parity composition and birth timing. The accuracy of MAC in identifying the timing of period fertility and the policy implications of timing on upturning fertility level are discussed.

Keywords:  Mean Age at Childbearing, Parity Composition, Fertility Postponement, Low Fertility Level, The Populations of China, Japan and South Korea