Preterm birth and social inequality: assessing the effects of material and psychosocial disadvantage in a UK birth cohort

ObjectiveTo examine the association between social inequalities and preterm birth, testing both psychosocial and material determinants. DesignRetrospective cohort study with linked hospital data. Setting and population17285 women in England, Scotland, Northern Ireland and Wales giving birth to singletons included in wave 1 of the UK Millennium Cohort Study. MethodsSocial inequalities were measured with material (household income, housing tenure) and psychosocial (education, occupational class, employment, social support) indicators. Analysis using multivariable logistic regression assessed odds of preterm birth, adjusting for demographics, health and health-related behaviors, pregnancy and delivery conditions, and pregnancy complications. Main outcome measurePreterm birth between 24 and 36weeks, 6days' gestation. ResultsInitial bivariable analysis suggested associations between preterm birth and household income, housing tenure, and education. These effects were largely explained by adjustment for other social determinants in multivariable models. Following full adjustment, effects of unemployment [OR=1.52, 95% confidence interval (CI) 1.21-1.90, p<0.001] and one indicator of poor social support (OR=1.17, 95% CI 1.01-1.35, p=0.04) remained significant. ConclusionUnemployment and lack of social support are associated with higher risk of preterm birth, supporting the hypothesis that poor psychosocial circumstances elevate a woman's risk of this adverse perinatal outcome. Further research is needed to examine the causal pathways through which social inequalities affect preterm birth.