The normal range of fetal heart rate is 110-160 beats/min, and it can also fluctuate between 110-180 beats/min, so a fetal heart rate of 152 beats/min is normal. Heart rhythm refers to the rhythm of the heartbeat, and heart rhythm is different from heart rate. Fetal heart rate of 152 beats/min means that the heart beats at a frequency of 152 beats per minute, while the beat intervals are not necessarily equal and the rhythm is not necessarily normal. Fetal arrhythmia is mainly divided into irregular heart rate, bradycardia less than 100 beats/min, and tachycardia >180 beats/min. Irregular heart rate is the most common, mainly caused by pre-term contractions, including atrial pre-term contractions and ventricular pre-term contractions, occurring more than 10 times per minute is called frequent pre-term contractions. Therefore, a rigorous evaluation of fetal heartbeat should be that the fetal heart rate is 152 beats/min and the rhythm is normal, but usually the ultrasound report form in the workplace only shows the fetal heart rhythm is normal, because if an abnormal rhythm appears, the ultrasound diagnosis will add another conclusion.