HR on the monitor is the medical English abbreviation for fetal heart rate, which is the number of times the heart beats per minute. The normal range of fetal heart rate is 120 to 160 beats per minute. Generally, the fetal heart rate is within the normal range, but the specific value will decrease with the increase of pregnancy weeks. A fast or slow fetal heart rate is generally indicative of intrauterine hypoxia. Fetal heart rate monitoring with ultrasound Doppler fetal cardiography is not routinely required until 15 weeks of gestation. For women between 15 and 28 weeks of gestation, it is safe to measure the fetal heart rate three times a day for one minute each time. For pregnancies after 28 weeks of gestation, the duration and frequency of monitoring can be extended moderately. For pregnant women with high-risk factors for pregnancy, such as hypertension and hyperthyroidism, close monitoring of the fetal heartbeat and regular checkups as prescribed by the doctor are needed.