The Illinois Transgenerational Birth File: Life-Course Analysis of Birth Outcomes Using Vital Records and Census Data Over Decades

We endeavored to construct a transgenerational birth file (TGBF) for use in longitudinal research on perinatal outcomes; such a file should contain social context data for women at the time of their own birth and the birth of their offspring. Births in Illinois from 1989 to 1991 were linked to the birth records of their mothers (and when possible, their fathers) born in Illinois between 1956 and 1976 (N = 267,303), on the basis of each parent's complete name and exact date of birth. Mortality data (survival or death) were then linked to each transgenerational record. Neighborhood median family income from census files was merged by geographic code to records from the Chicago area. An infant-mother match rate of 78% was achieved, and about half of these paired records could also be matched to fathers. For Chicago area births (N = 97,755), linkage to census data was also completed for nearly 100% of records, allowing us to characterize the economic situation of the mother at the time of her birth as well as when she had her own baby. Analysis of the TGBF showed a slight bias toward more educated parents compared to the total state population, especially the subset with successful match to both parents. The infant mortality, LBW, and VLBW rates in the TGBF population differed little from the overall rates for Illinois. This project demonstrates the feasibility of creating a data set for studying outcomes of childbearing women within a lifetime social and economic context in a US population. Despite some bias in exclusion of less educated parents, mortality and LBW rates suggest that the TGBF is fairly representative with regard to important infant health outcomes.