There is a popular belief that the fetal heart rate (FHR) of male fetuses is lower than that of female fetuses. However， this idea is only partially true and based on limited evidence. In reality， a number of factors can influence the FHR， including gestational age， maternal age， fetal activity， and maternal health.
One factor that can affect the FHR is gestational age. During the first trimester， the FHR of male and female fetuses is similar， as both range between 110 and 180 beats per minute. However， after the 12th week of pregnancy， the FHR tends to slow down and stabilize. At this point， there may be a slight difference between the FHR of male and female fetuses， with male fetuses having a slightly lower FHR on average.
Another factor that can influence the FHR is fetal activity. Fetal movement can cause temporary increases or decreases in the FHR， which can be misinterpreted as a sign of gender difference. However， these changes are normally brief and do not reflect a consistent pattern.
Maternal health and age can also impact the FHR. For example， maternal illnesses such as diabetes or high blood pressure can cause fetal distress and a lower FHR. In addition， older maternal age can lead to changes in placental blood flow， which can affect the FHR.
Overall， it is important to remember that the FHR can vary widely from one pregnancy to another， and is not a reliable indicator of fetal gender. Ultrasound is a more accurate method of determining fetal sex. However， the FHR is still an important measure of fetal health and should be monitored throughout pregnancy by a healthcare professional.
