The population structure of the Amish, a rapidly growing ethnic religion in North America.

As Western populations face projected decline, understanding the demographics of high-fertility subpopulations becomes increasingly important. The Amish represent one rapidly growing North American subgroup, yet existing demographic studies are dated and narrowly focused. Here, we use a new population database of >50,000 households-the vast majority of Amish-to offer an up-to-date population-wide analysis that shows high fertility and low mortality and attrition. Specifically, women's median age at marriage is 20.9, and 87.1 per cent marry by age 50; premarital conceptions are low (4.30 per cent of first births); spacing between marriage and first birth is short (mean 17.2 months); the total fertility rate is 6.1; infant mortality is 5.9; life expectancy at birth is 81.16 years; attrition is low (84.46 per cent retention for those aged 40+); and in-conversion is very low (154 individuals across nearly a century). These definitive population-wide figures open the way for testing predictors of population change and charting how growing subpopulations are shaping regions.