Temporal changes in socioeconomic influences on health: maternal education and preterm birth.

Abstract

To consider how the relationships between social determinants and health indicators change over time, we assessed the time-varying influence of maternal education on risk of preterm birth (PTB) between 1989 and 2006. We used bivariate and multivariable Poisson regression models with robust variation estimates to examine (1) the association between maternal education and PTB risk by year; (2) the relationship between low maternal education and PTB, late PTB, and very PTB risk by year relative to 1989; and (3) the relationship between high maternal education and PTB, late PTB, and very PTB risk by year relative to 1989. After adjustment, PTB risk increased among the most educated and did not change among the least educated women over time. Risk of PTB among the least educated relative to the most educated women decreased with time. Late PTB risk increased among both the most and the least educated groups but more among the most educated. Maternal education may be becoming less protective against PTB. The influence of the social determinants of health is dynamic, warranting revisions of our understanding of their roles over time.