Long-Term Trends of the Number of Children and Age-Specific Fertility Rates of Japanese Women

Ikuko Funatogawa, The Institute of Statistical Mathematics

Childbirth generally occurs at ages between the late teens and mid-40s in women, but typical age range or typical number of children can vary according to the calendar year or birth year. Childbirth will affect a woman’s lifestyle and health later in life, as well as their mortality and other future outcomes. Therefore, it is important to take the birth year into account. Therefore, we estimated long-term trends in the number of children born to Japanese women according to birth year. Using the number of children born to Japanese wives aged mainly 45–49 from the population census and the national fertility surveys conducted during 1950 and 2021, we estimated the distribution of the number of children among Japanese women born between 1890 and 1973, adjusted by the female unmarried rate. Because this distribution was a rough estimate based on 5- year age intervals, we further confirmed detailed changes in the age-specific fertility rate at 1-year age intervals. The distribution of number of children changed largely between late 1900s and around 1930s birth cohorts.

Keywords: Fertility, Census data, Data visualisation , Historical Demography

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