RESUMEN
OBJECTIVE: To evaluate the five-tier classification of fetal heart rate (FHR) tracings recently proposed by Japan Society of Obstetricians and Gynecologists (JSOG). METHODS: The database between January and June 2009 was reviewed for women in active labor at ?36 + 0 gestational weeks, with singleton fetuses in cephalic presentation and with umbilical artery blood gas analyses. Continuous FHR tracings were assessed according to the five-tier classification proposed by JSOG, where level 1 is normal, level 2 is subnormal and levels 3?5 are abnormal patterns. RESULTS: A total of 341 parturient women were eligible for this study protocol. The median (range) of the levels in the first and the second stage of labor were 1 (1-4) and 2 (1-4), respectively (p < 0.001). Both pH and base excess of umbilical artery decreased with higher levels of FHR tracings interpretation (p < 0.01). Interventions resulting in delivery were more necessary in the first stage of labor than in the second stage of labor in cases of levels 3 and more. CONCLUSIONS: Five-tier system for FHR tracing interpretation proposed by JSOG intercorrelates with the fetal acid-base balance well. Categorization of FHR tracings by uniform diagnostic criteria will be useful to standardize therapeutic strategy by sharing common perception among obstetrical staff.
