Modern medicine proves that the asphyxia, fetal distress and umbilical cord around neck(25% of pregnant has such situation) will affect the normal growing development of fetal, sometimes there will be dangerous to the fetus, even to the mother, and these

symptoms will make the fetal heart rate changed abnormally, so the fetal heart range gives an indication of fetal well-being.if conditions permit, pregnant women over 16 weeks are recommended to listen to the fetal heart sound for 1-2 minutes per time, three times per day(within 30 minutes after getting up, within 60 minutes after lunch, and within 30 minutes going to sleep)