Interobserver and intraobserver reliability of the NICHD 3-Tier Fetal Heart Rate Interpretation System

Objective Our purpose was to test the reliability of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) 3-Tier Fetal Heart Rate (FHR) classification system. Study Design Individual 15- to 20-minute FHR segments (n = 154) were independently reviewed without clinical data by 3 maternal-fetal medicine examiners and classified by NICHD category (I, II, III). Results Interobserver reliability was moderate (kappa 0.45) and varied by NICHD category (category I moderate [kappa 0.48], category II moderate [kappa 0.44], and category III poor [kappa 0.0]). The intraobserver agreement ranged from substantial to perfect (kappa 0.74-1.0). Conclusion Interobserver agreement of 3-Tier FHR classification System was moderate for NICHD categories I and II. Agreement for category III tracings was poor mainly due to lack of agreement regarding absent vs minimal variability.