This health page was created to help pregnant women who have not been able to detect a heartbeat in early stages of pregnancy. I see this question posted a lot in the pregnancy forum, so I have decided to dig up some facts and do research on this topic. I hope it helps answer some of the questions members have about seeing or hearing a fetus' heartbeat before 8 weeks.
How and when a fetal heartbeat can be detected
1. An ultrasonic examination with apparatus based on the Doppler effect will under certain conditions make it possible to detect the fetal heartbeat beginning with the 7th to 8th week of pregnancy. When a pregnancy is over 13 weeks, the life or death of a fetus is established with certainty.
When can I see a fetus on an ultrasound Scan
The gestational sac can be visualized as early as four and a half weeks of gestation and the yolk sac at about five weeks. The embryo can be observed and measured by about five and a half weeks. Ultrasound can also very importantly confirm the site of the pregnancy is within the cavity of the uterus.
Sometimes a fetus is not found when a woman has ovulated later than suspected. If a fetus or gestational sac is not found by 6 weeks gestation then a second ultasound should take place 1-2 weeks later.
Normal Fetus Heart Rate
Normal heart rate at 6 weeks is around 90-110 beats per minute (bpm) and at 9 weeks is 140-170 bpm. At 5-8 weeks a bradycardia (less than 90 bpm) is associated with a high risk of miscarriage.
A regular heart rate of 140-170 is maintained at 8 weeks gestation.
If a normal heart rate is not detected by a transvaginal ultrasound at 9 weeks gestation, then your doctor may suspect a miscarriage.