Explaining educational inequalities in preterm birth: the generation r study

Background: Although a low socioeconomic status has consistently been associated with an increased risk of preterm birth, little is known about the pathways through which socioeconomic disadvantage influences preterm birth. Aim: To examine mechanisms that might underlie the association between the educational level of pregnant women as an indicator of socioeconomic status, and preterm birth. Methods: The study was nested in a population-based cohort study in the Netherlands. Information was available for 3830 pregnant women of Dutch origin. Findings: The lowest-educated pregnant women had a statistically significant higher risk of preterm birth (odds ratio (OR) = 1.89 (95% CI 1.28 to 2.80)) than the highest educated women. This increased OR was reduced by up to 22% after separate adjustment for age, height, preeclampsia, intrauterine growth restriction, financial concerns, long-lasting difficulties, psychopathology, smoking habits, alcohol consumption, and body mass index (BMI) of the pregnant women. Joint adjustment for these variables resulted in a reduction of 89% of the increased risk of preterm birth among low-educated pregnant women (fully adjusted OR = 1.10 (95% CI 0.66 to 1.84)). Conclusions: Pregnant women with a low educational level have a nearly twofold higher risk of preterm birth than women with a high educational level. This elevated risk could largely be explained by pregnancy characteristics, indicators of psychosocial well-being, and lifestyle habits. Apparently, educational inequalities in preterm birth go together with an accumulation of multiple adverse circumstances among women with a low education. A number of explanatory mechanisms unravelled in the present study seem to be modifiable by intervention programmes.