Outline of the Sixth Longitudinal Survey of Babies in 21st Century

Ministry of Health, Labour and Welfare

Japanese

Summary of the Survey Results

1. Family Status

(1) Sibling Composition

Over 40% of all the survey subjects had younger sibling(s).

According to changes in the sibling composition, those who were the only child made up 48.8% and elder sibling(s) only 51.2% of all survey subjects in the 1st survey (aged 6 months). In the 6th survey (aged 66 months), those who were the only child made up 16.3% and elder sibling(s) only 41.4%. However, as they had new brother(s) or sister(s) over the years, 42.3% of all survey subjects had younger sibling(s) in the 6th survey (Figure 1).

Figure 1 Changes in the sibling composition

Figure 1  Changes in the sibling composition
Note: The figures are based on the total number of responses to the 1st through 6th surveys, excluding the
replies with “unknown” concerning sibling composition (total number of replies: 35,632).

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