It is not accurate to identify a brother or a sister by fetal heartbeat; fetal heartbeat does not identify gender.
Fetal heart, the heartbeat of the fetus, can reflect the state of the fetus in the womb. There is generally no such thing as determining the sex of a fetus by the speed of the fetal heart, because there may be differences in the fetal heart rate of both male and female babies. Moreover, the fetal heart test can only determine the general condition of the fetus in the uterus, and it is likely to have an impact on the life of the fetus if the fetal heart is abnormal.
The normal range of fetal heart rate is between 110-160 beats per minute, and the fetal heart can change very sensitively when the fetus is deprived of oxygen for various reasons.
Tachycardia is defined as more than 160 beats/minute for more than 10 minutes. Bradycardia is defined as when the fetal heart rate is less than 110 beats/minute and lasts for more than 10 minutes. Whether it is bradycardia or tachycardia, it is important to watch out for intrauterine hypoxia.
It is recommended to do regular checkups and seek medical attention if there is any abnormality in the fetal heartbeat to avoid serious consequences.