Introduction Social inequalities in pregnancy outcomes have been extensively described, but studies that explain these inequalities comprehensively are lacking. This analysis evaluated the contribution of material, psychosocial, behavioural, nutritional, and obstetrical factors in explaining social inequalities in preterm delivery.
Methods The data were based on a prospective cohort of 1109 Irish pregnant women. Preterm delivery was obtained from clinical hospital records. Socio-economic status was measured using educational level. The association between educational level and preterm delivery was examined using Cox model.
Results Educational level was found to be a significant predictive factor of preterm delivery; women with low educational level were more likely to have a preterm delivery (HR=2.14, 95% CI 1.04 to 4.38) after adjustment for age and parity. Rented and crowded home, smoking, alcohol consumption, and intake of saturated fatty acids displayed educational differences and were predictive of preterm delivery. Material factors (rented and crowded home) reduced the HR of preterm delivery for low educated women by 33%. The independent contribution of behavioural factors (smoking and alcohol consumption) from material factors was 5%, and the independent contribution of saturated fatty acids from material to behavioural factors was 4%. All these factors together reduced the HR of preterm delivery for low educated women by 42% (HR=1.66, 95% CI 0.76 to 3.63).
Conclusion This study is one of the first to attempt to explain social inequalities in preterm delivery comprehensively, and underlines the importance of material, behavioural and nutritional factors. More research is needed to better understand and prevent social inequalities in preterm delivery.