%0 Journal Article
%T Mediating roles of preterm birth and restricted fetal growth in the relationship between maternal education and infant mortality: A Danish population-based cohort study
%A Aolin Wang
%A Bo Fu
%A Carsten Obel
%A Guoyou Qin
%A Jialiang Li
%A Jiong Li
%A Jˋrn Olsen
%A Onyebuchi A. Arah
%A Sven Cnattingius
%A Yongfu Yu
%A Zeyan Liew
%J -
%D 2019
%R 10.1371/journal.pmed.1002831
%X Background Socioeconomic disparities in infant mortality have persisted for decades in high-income countries and may have become stronger in some populations. Therefore, new understandings of the mechanisms that underlie socioeconomic differences in infant deaths are essential for creating and implementing health initiatives to reduce these deaths. We aimed to explore whether and the extent to which preterm birth (PTB) and small for gestational age (SGA) at birth mediate the association between maternal education and infant mortality.   Methods and findings We developed a population-based cohort study to include all 1,994,618 live singletons born in Denmark in 1981每2015. Infants were followed from birth until death, emigration, or the day before the first birthday, whichever came first. Maternal education at childbirth was categorized as low, medium, or high. An inverse probability weighting of marginal structural models was used to estimate the controlled direct effect (CDE) of maternal education on offspring infant mortality, further split into neonatal (0每27 days) and postneonatal (28每364 days) deaths, and portion eliminated (PE) by eliminating mediation by PTB and SGA. The proportion eliminated by eliminating mediation by PTB and SGA was reported if the mortality rate ratios (MRRs) of CDE and PE were in the same direction. The MRRs between maternal education and infant mortality were 1.63 (95% CI 1.48每1.80, P < 0.001) and 1.19 (95% CI 1.08每1.31, P < 0.001) for low and medium versus high education, respectively. The estimated proportions of these total associations eliminated by reducing PTB and SGA together were 55% (MRRPE = 1.27, 95% CI 1.15每1.40, P < 0.001) for low and 60% (MRRPE = 1.11, 95% CI 1.01每1.22, P = 0.037) for medium versus high education. The proportions eliminated by eliminating PTB and SGA separately were, respectively, 46% and 11% for low education (versus high education) and 48% and 13% for medium education (versus high education). PTB and SGA together contributed more to the association of maternal educational disparities with neonatal mortality (proportion eliminated: 75%每81%) than with postneonatal mortality (proportion eliminated: 21%每23%). Limitations of the study include the untestable assumption of no unmeasured confounders for the causal mediation analysis, and the limited generalizability of the findings to other countries with varying disparities in access and quality of perinatal healthcare.   Conclusions PTB and SGA may play substantial roles in the relationship between low maternal education and infant mortality,
%K Preterm birth
%K Infants
%K Death rates
%K Socioeconomic aspects of health
%K Labor and delivery
%K Denmark
%K Birth
%K Danish people
%U https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002831