Ospina M, Osornio-Vargas AR, Nielsen CC, et al. - Researchers conducted a cross-sectional study applying a validated perinatal clinical registry and an area-level socioeconomic status (SES) to analyze the distribution of adverse birth outcomes (ABO) and related maternal risk factors across area-level socioeconomic status (SES) gradients in urban and rural Alberta, Canada. A total of 330,957 women having singleton live births with gestational age ≥ 22 weeks were included in Alberta, Canada between 2006 and 2012. The concentration indexes were calculated to evaluate inequalities across SES gradients in both rural and urban areas (CIdxR and CIdxU, respectively) for spontaneous preterm birth (PTB), small for gestational age (SGA), large for gestational age, gestational hypertension, gestational diabetes, smoking and substance use during pregnancy and pre-pregnancy weight > 91 kg. The results of this study displayed that ABO and associated maternal risk factors were unevenly distributed across the socioeconomic gradient in urban-rural settings, with the greatest concentrations in lower SES groups of rural areas.