Addressing selective outcome reporting and reference group biases in perinatal epidemiology of adverse birth outcomes

Although both extremes of gestational age and birth weight are critical, the disproportionate and predominant focus on the lower extremes of ABOs contributes to selective outcome reporting bias, hindering complete understanding of the full spectrum of ABOs for evidence-based decision-making. Future studies should consider each ABO as trinomial rather than binary classification, whether as an outcome, exposure, or covariate variable, and use the appropriate reference groups (term birth, normal birth weight, and appropriate for gestational age). These will address both reporting and reference group biases, which are essential to improve the accuracy and applicability of perinatal research on ABOs.