Validity of the Spanish surname infant mortality rate as a health status indicator for the Mexican American population.

This study assessed the validity of the Spanish surname infant mortality rate as an index of urban Mexican American health status. Neonatal, postneonatal, and risk-factor-specific mortality rates were computed from linked birth and infant death records of the 1974-75 Harris County, Texas, cohort of 68,584 for Spanish surname White, non-Spanish surname White, and Black single live births. Infants of Mexican-born immigrants were distinguished from those of other Spanish surname parents by parental nativity information on birth records. Infants of Mexican immigrants had paradoxically low mortality rates for high birth order, high maternal age, and delayed or absent prenatal care; only infants weighing less than 1500 gm showed expected high rates. Findings suggested loss of infant death data compatible with migration and under-registration of deaths. The Spanish surname infant mortality rate may be spuriously low and does not appear to be a valid indicator of Mexican American health status even in an urban, non-border area considered to have excellent birth and death registration.