Fetal heart monitoring fluctuates too much may be due to physiological or pathological reasons, physiological reasons include temporary compression of the fetal trunk and umbilical cord, contractions, etc. Pathological reasons include intrauterine distress and acidosis. 1. Physiological causes. (1) Temporary pressure on the fetal trunk and umbilical cord: if the fetal heart rate accelerates to 15-20 beats/minute, it means that the fetal trunk and umbilical cord may be under pressure causing too much fluctuation of the fetal heart rate, and if it belongs to the transient changes, it means that the fetus is developing well in the uterus. (2) Contraction: the phenomenon of too much fluctuation of the fetal heart will occur with contraction, if the decrease of the fetal heart <40 beats/min. This indicates that the pressure on the fetal head increases, leading to reflex slowing of the fetal heart, which can be gradually recovered after contraction, and generally has little effect on the fetus. 2. Pathologic causes. (1) Fetal intrauterine distress: such as maternal anemia, umbilical cord around the neck, maternal use of analgesics, etc., can cause intrauterine distress, fetal ischemia, hypoxia, and if the fetal heart deceleration lasts for a long time, it will affect fetal development. (2) Fetal acidosis: if the fetus continues to lack of oxygen can lead to metabolic acidosis, easy to cause fetal heart fluctuations, and even cause fetal death in the womb. Fetal heart fluctuation is too large phenomenon, it is recommended that pregnant women go to the hospital in time to do fetal heart monitoring, to find the cause, if necessary, timely treatment.