-Original-

Fetal Heart Rate Classification Proposed by the Perinatology Committee of the Japan Society of Obstetrics and Gynecology: Reproducibility and Clinical Usefulness

Masako Hayashi, Akihito Nakai, Atsuko Sekiguchi and Toshiyuki Takeshita

Division of Reproductive Medicine, Perinatology and Gynecologic Oncology, Graduate School of Medicine, Nippon Medical School

Aim: Intrapartum management guidelines based on fetal heart rate classification comprising a 5-tier system (Levels 1-5) was proposed by the Perinatology Committee of the Japan Society of Obstetrics and Gynecology (JSOG). This study aimed to assess the reproducibility and clinical usefulness of this classification.
Methods: For assessing intraobserver and interobserver reproducibility in the interpretation of fetal heart rate tracing, 2 obstetricians reviewed 247 fetal heart rate tracings using the JSOG classification (Level 1, normal; Level 2, benign variant; Level 3, mild variant; Level 4, moderate variant; and Level 5, severe variant) and a subjective 3-tier classification (normal, equivocal, and ominous). In a separate series, we investigated whether the JSOG classification is related to early neonatal outcome and the delivery mode in 96 deliveries.
Results: Weighted kappa coefficients of intraobserver and interobserver reproducibility in the interpretation of fetal heart rate tracings based on the JSOG classification were 0.73 to 0.77 and 0.70, respectively. In the subjective classification, these values were 0.69 to 0.72 and 0.59. There was a progressive increase in the rate of instrumental or cesarean deliveries across the 5 levels of the JSOG classification (P<0.001). Although, level 5 of the JSOG classification had a lower Apgar score and umbilical artery pH than did the other 4 levels (p<0.05), there were no significant differences among the other levels in regard to early neonatal outcome.
Conclusions: This study demonstrated that both intraobserver reproducibility and interobserver reproducibility of the JSOG classification for interpreting FHR tracings were clinically acceptable. The results also suggest that the intervention according to the JSOG classification is useful for avoiding worsening early neonatal outcomes.

J Nippon Med Sch 2012; 79: 60-68

Keywords
cardiotocography, classification, fetal heart rate, guideline, early neonatal outcome

Correspondence to
Masako Hayashi, MD, Department of Obstetrics and Gynecology, Nippon Medical School Tama Nagayama Hospital, 1-7-1 Nagayama, Tama, Tokyo 206-8512, Japan
hayashi@nms.ac.jp

Received, May 21, 2011
Accepted, September 12, 2011