Fetal heart rate (FHR) 165 does not directly determine whether a fetus is a brother or a sister. Fetal heart rate is also known as the heart rate of the fetus, and monitoring the fetal heart rate can reflect the state of the fetus in the uterus. The sex of the fetus is determined by the sex chromosomes, and there is no scientific basis for distinguishing whether it is a boy or a girl using the fetal heart rate. Monitoring the fetal heart rate can understand the baby’s health status in the uterus, the normal value of the fetal heart 110-160 beats / min, the fetal heart 165 beats / min is higher than the normal value, need to be combined with the pregnant woman’s condition and fetal movement, continuous observation, such as persistent rapidity for 10 minutes to consider the tachycardia, it is recommended to consult a doctor in a timely manner. Pregnant women should go to the hospital regularly for maternity checkups to check the health of the fetus, and if abnormalities are found, they should actively cooperate with the doctor for treatment to avoid adverse effects.