A 4D fetal heart rate above 150 cannot be used to determine if it is a boy or girl baby. Fetal heart rate refers to the heart rate of the fetus and has nothing to do with the sex of the fetus. Fetal heart rate is an important indicator of fetal activity, fetal heart condition, and whether the fetus is suffering from hypoxia through external monitoring. The normal fetal heart rate is 110-160 beats per minute. The sex of the fetus is determined by the combination of the parents’ chromosomes. The sex of the fetus is female when the sperm carrying the X chromosome combines with the egg carrying the X chromosome, and male when the sperm carrying the Y chromosome combines with the egg carrying the X chromosome. The sex of the fetus is determined at the time of fertilization of the egg, and is not directly related to the value of the fetal heart rate. Four-dimensional fetal heart rate of 150 or more can not determine the sex of the fetus, at present in our country to identify the sex of the fetus is illegal, can not be carried out without authorization.