The magnitude and population burden of educational inequalities in adverse birth outcomes

We aimed to describe the magnitude and population burden of inequality in adverse birth outcomes by maternal education (five categories). Data from 639,007 singleton births of gestational age ≥ 24 weeks or, if missing, birthweight ≥ 500 g were included from the National registry of the Netherlands, 2016-2019. One in six Dutch births had an adverse outcome. Each step down the educational ladder was associated with higher adverse outcome rates. Inequalities in stillbirth and neonatal mortality rates were large between the highest (Master's or higher) and lowest (primary) educated groups (rate ratio [RR] = 2.94 [95%CI: 2.33-3.55] and 2.25 [1.71-2.79], respectively). Inequalities were smaller for preterm birth, small-for-gestational-age, low Apgar score, neonatal intensive care unit admission, and severe congenital anomalies (RR range = 1.32-1.77; PAF range = 13.8-17.7%). Mortality would reduce by a third if the entire population had the mortality rates of the highest educated (population attributable fraction [PAF]_stillbirth=35.0% [24.4-45.6%]; PAF_{neonatal mortality}=27.1% [14.4-39.7%]). The middle education category (higher secondary) was the largest group, contributing most to the population burden of inequality despite only having a moderately elevated risk of adverse outcomes. Population health gains would be largest if addressed through preventive approaches targeting the entire health gradient rather than by only focussing on those at highest risk.