Association between the cumulative duration of abnormal cardiotocography patterns and fetal acidemia

Incorporating the cumulative duration of CTG abnormalities into the JSOG five-tier classification may improve the assessment of fetal acidemia risk. Our time-based analysis demonstrated that LEVEL-specific CTG abnormalities and fetal tachycardia showed duration-related associations with acidemia, particularly during the first stage of labor. LEVEL 3 abnormalities and fetal tachycardia during the first stage of labor were more associated, whereas LEVELS 4 and 5 abnormalities during the second stage were more associated with acidemia. These findings may facilitate more informed intrapartum decision-making by identifying fetuses at risk earlier in labor, potentially reducing unnecessary emergency cesarean deliveries and preventing severe acidemia.