Trends in cohort fertility of the Dariusleut Hutterite population.

A cohort analysis of marital fertility among Hutterite women living in the Dariusleut clan in South Dakota in the US revealed that the marital age specific fertility rate (ASFR) for women aged 20-24 years increased between the 1901-05 cohort and the 1921-35 cohort during a period when the number of reproductive age women declined. For women aged 40-44 years there was a gradual decline. The average number of children born to the 1901-05 and 1921-35 cohorts ranged between 7.45 and 8.56 children. After the 1935 cohort fertility began to decline for all ages over 20 years. The decrease among women aged 20-29 years was small and in the 1951-55 cohort women aged 20-29 years had 4.52 children which was still larger than 4.26 children for the 1901-05 cohort. Mean age at marriage increased from the 21.5 years for the 1901-05 cohort to 22.5-23.5 years for the 1926-30 cohort without an appreciable change in fertility. The beginning of fertility decline among the 1931-35 cohort appeared without a major change in age at marriage. A one-year increase in marriage age for the 1936-40 cohort may have added to fertility decline. Marriage age did not change much thereafter but fertility did. Fertility declines after the 1936 cohort were attributed to the decreases in the marital ASFR particularly among those aged 30 years and older. The fertility decline among older women may have been due to the influence of family doctors and better medical care. Data on the 13 five-year cohorts born between 1901 and 1965 were obtained from church records for the Dariusleut population living in 125 colonies with a total population of 10000. Data were aggregated at Teikyo University Tokyo Japan by colony family name family number birth date marriage date baptism date and death date. 2447 females were born in the study period but vital data were available for 2432 females of which 7.6% died before the age of 20 years. 75% of the 2247 remaining were married by 1988. Analysis was performed with a sample of 1682 women.