The Edmonton Obesity Staging System and pregnancy outcomes in women with overweight or obesity: A secondary analysis of a randomized controlled trial

The Edmonton Obesity Staging System (EOSS) is a proposed clinical practice tool to determine obesity severity. In a secondary analysis of the Pregnancy Exercise and Research Study (PEARS) (a mobile-health-supported lifestyle intervention among pregnant women with body mass index [BMI] ≥25 kg/m² ), we apply the EOSS and explore relationships with pregnancy outcomes. In early (14-16 weeks) and late (28 weeks) pregnancy, fasting lipids and glucose were measured, blood pressure was extracted from medical records and maternal well-being was assessed using the WHO-5 Well-being Index. Pearson's correlations, chi-square statistics and multiple logistic regression were used to identify relationships. One-way analysis of variance was used to compare groups. Pregnant women (n = 348) were mean (SD) age 32.44 (4.39) years and median (interquartile range) BMI 28.0 (26.57, 29.88) kg/m² . Using metabolic criteria only, 81.9% and 98.9% had raised EOSS scores in early and late pregnancy. From early to late pregnancy, EOSS scores increased by 60.1%. Of these, 10.5% experienced a 2-point increase, moving from stage 0 to stage 2. There was a potential relationship between early EOSS and large for gestational age (χ² = 6.42, df (2), p = .04), although significance was lost when controlled for confounders (p = .223) and multiple testing. Most women with BMI ≥25 kg/m² had raised EOSS scores, limiting the clinical utility of the tool.