We investigated the relationship between maternal age at first birth and long-term mortality. We conducted a cohort study of 20,624 parous Japanese women aged between 40 and 79 years in 1994 and followed up their survival for 14 years. Based on maternal age at first birth, the women were divided into four groups: ≤19 years, 20-24 years, 25-29 years, and ≥30 years. Using the 20-24 years group as a reference, hazards ratios (HRs) for all-cause and cause-specific mortality were calculated. Multivariate HRs for all-cause mortality were 1.17 in the ≤19 years group, 1.09 in the 25-29 years group, and 1.33 in the ≥30 years group. A U-shaped relationship was apparent between maternal age at first birth and mortality. This relationship was also observed for mortality attributable to cancer, cardiovascular disease and other diseases. This U-shaped relationship was observed only for women born before 1935 and the birth year of the first child before 1960.（40~79歳の20,624人の日本人経産婦を対象に、1994年から14年間の追跡調査により、初産年齢と死亡率の関連を調査した。初産年齢20-24歳を基準としたとき、死亡率のハザード比は19歳以下で1.17、25-29歳で1.09、30歳以上で1.33であり、U字型の関連がみとめられた。ただし、この関連は、1935年以前に生まれた女性、1960年以前に初産であった女性にのみみとめられた。）
p.761-782
Sakai Taichi
Sugawara Yumi
Watanabe Ikue
Watanabe Takashi
Tomata Yasutake
Nakaya Naoki
Tsuji Ichiro
