The sex of the fetus cannot be determined by the frequency of the fetal heart, and there is no scientific basis for this identification. Fetal heartbeat data cannot be used as a basis for distinguishing the sex of the fetus. Fetal heartbeat data generally reflects the state of the fetus in the uterus. If the fetal heartbeat is too fast or too slow, it means that the fetus may have abnormalities in the uterus, and the fetus may be suffering from intrauterine oxygen deprivation. The sex of the fetus can generally be determined by ultrasound after the fetus is sixteen weeks old, when the reproductive organs of the fetus have already developed, and the sex of the fetus can be determined by ultrasound. However, it is important to note that non-medical fetal sex identification is illegal in China. In addition, it is recommended that pregnant mothers relax, whether it is a boy or a girl, as long as the fetus is healthy in the womb.