What is the “normal” fetal heart rate?

Abstract

Aim. There is no consensus about the normal fetal heart rate. Current international guidelines recommend for the normal fetal heart rate (FHR) baseline different ranges of 110 to 150 beats per minute (bpm) or 110 to 160 bpm. We started with a precise definition of “normality” and performed a retrospective computerized analysis of electronically recorded FHR tracings.Methods. We analyzed all recorded cardiotocography tracings of singleton pregnancies in three German medical centers from 2000 to 2007 and identified 78,852 tracings of sufficient quality. For each tracing, the baseline FHR was extracted by eliminating accelerations/decelerations and averaging based on the “delayed moving windows” algorithm. After analyzing 40% of the dataset as “training set” from one hospital generating a hypothetical normal baseline range, evaluation of external validity on the other 60% of the data was performed using data from later years in the same hospital and externally using data from the two other hospitals.Results. Based on the training data set, the “best” FHR range was 115 or 120 to 160 bpm. Validation in all three data sets identified 120 to 160 bpm as the correct symmetric “normal range”. FHR decreases slightly during gestation.Conclusions. Normal ranges for FHR are 120 to 160 bpm. Many international guidelines define ranges of 110 to 160 bpm which seem to be safe in daily practice. However, further studies should confirm that such asymmetric alarm limits are safe, with a particular focus on the lower bound, and should give insights about how to show and further improve the usefulness of the widely used practice of CTG monitoring.

Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis

“…Indeed, a large cohort study by Pildner von Steinburg et al 109 showed the incidence of bradycardia and tachycardia at rest (exercise was not examined) to be 0.12% and 3.71%, respectively, whereas we reported a 95% CI of 0% to 3% for bradycardia and 0% to 14% for tachycardia. Future studies looking at FHR longitudinally (ie, comparing incidence of bradycardia and tachycardia at rest, during and following exercise) are required.…”

Recreating the Cardiac Microenvironment in Pluripotent Stem Cell Models of Human Physiology and Disease

“…Biphasic stimulation compared to monophasic stimulation decreases the excitation threshold and increases cell viability [107]. When hPSC-CMs resemble immature fetal CMs, electric stimulation at 1Hz is non-physiologic since the fetal heart has a beating rate between 2 and 3Hz [110]. In a recent study, stimulation at 6 Hz promoted cellular and functional maturation of hPSC-CMs [108].…”

Ultrasound transducer positioning aid for fetal heart rate monitoring

“…A counter weight prevents the heart phantom from floating away and guarantees a stable sinusoidal motion pattern. The adjustable driving voltage of the motor is set such that it simulates the normal average fetal heart rate of 140 beats per minute [7]. The distance between the rotary hinge and the motor was tuned, such that the distance covered by the phantom during one cycle is equal to the distance covered by the fetal cardiac wall during one heart beat, i.e.…”