Vieira MC, et al. - Given that comparison of birth-weight charts, to determine which better identify infants at risk of adverse perinatal outcomes, has been done in many studied but with less attention to the threshold used to define small or large for gestational age infants, researchers used population, customized, and Intergrowth centile charts to ascertain the different thresholds associated with increased risk of adverse perinatal outcomes. In this population-based cohort study (Swedish Medical Birth Registry), which included term singleton births between 2006 and 2015 from women with available data on first-trimester screening, small and large infants had increased risk of adverse outcomes at different thresholds for each chart and the risks were also different according to the outcome studied. The charts exhibited different strength of association with adverse perinatal outcomes for infants below the 5th birth-weight centile (odds ratio [OR] 4.47, 95% confidence interval [CI] 3.30–6.04, P < 0.001 for the population chart; OR 5.78, 95% CI 4.22–7.91, P < 0.001 for the customised chart; OR 10.74, 95% CI 7.32–15.77, P < 0.001 for the Intergrowth chart) but exhibited similar strength of association in the smallest 5% of the population (OR 4.34, 95% CI 3.22–5.86, P < 0.001 for the population chart; OR 5.23, 95% CI 3.85–7.11, P < 0.001 for the customised chart; OR 4.69, 95% CI 3.47–6.34, P < 0.001 for the Intergrowth chart). They observed similar performance of these three charts to detect infants with adverse outcomes, such as perinatal mortality when using thresholds that reflect a false-positive rate of 10% for each chart.