Computerized analysis of fetal heart rate parameters by gestational age.

OBJECTIVE: The aim of this study is to define the reference ranges for fetal heart rate (FHR) parameters according to gestational age, by determining the relationship between the FHR and gestational age using a computerized FHR analysis system. METHODS: Using our own software developed by Hanyang University Hospital in Korea, non-stress tests were performed for 20 min. FHR parameters for 6455 subjects were analyzed for various gestational groups; <25 weeks, 25-28 weeks, 29-32 weeks, 33-36 weeks, 37-40 weeks, and >40 weeks. RESULTS: The FHR parameters were related to gestational age. The mean baseline FHR, signal loss, and fetal movements decreased significantly with gestation (P<0.0001). The variability and accelerations of FHR were highest for the 37-40 weeks gestational group (P<0.05). CONCLUSIONS: The results showed that overall, the differences in the FHR parameters between gestational groups were statistically significant, and the gestational age of the fetus should be considered when interpreting FHR patterns.