[Rate of incidence of divorce in birth cohorts classified by age difference between married couples].

We examined the situation concerning divorce in Japan from the view-point of age difference between married couples using vital statistics from the year 1952 to 1985. Annual and cumulative divorce rates were introduced as rate of incidence of divorce. We studied these indices by age difference between couples in birth cohorts of husbands. Our conclusions were as follows: 1) The cumulative divorce rate was lower in early birth cohorts than in late birth cohorts. 2) The cumulative divorce rate for young adult couples (aged 20-30) was higher than that for middle-aged couples (aged more than 30) in every cohort. 3) The cumulative divorce rate was lowest when husbands were 1 to 4 years older than wives. This tendency was quite similar in different ages and cohorts. 4) The same conclusions were reached when the annual divorce rate was substituted for the cumulative divorce rate.