When did your heart start to beat?

21 days after fertilization - the heart begins to beat. By 4 weeks, the heart typically beats between 105 and 121 times per minute.

See the very visible heartbeat in this foetal ultrasound

Hearing the Foetal Heartbeat

Doctors use several different methods to listen to the foetal heartbeat. At about 3 weeks when the heart first begins to beat, the sound of the little heart is too soft to hear. Very soon after this, they can see the motion using ultrasound technology. A doctor's stethoscope is not sensitive enough to hear the embryo's heart beating.

A special stethoscope called a fetoscope works well when the foetus is larger, usually around 15-17 weeks. [1] An active foetus however, can make this method of listening a bit challenging. Often when the fetoscope is finally in the right place on the woman's belly, her foetus will change positions and the doctor must move the stethoscope again in search of the fetal heartbeat.

The presence of a foetal heartbeat confirms pregnancy, as long as doctors are certain to distinguish the foetal heartbeat from the mother's. Usually this is not difficult as the foetus has a much faster heart rate than the mother.

Listen to the Foetal Heartbeat beating at 150 beats per minute

See how the heart develops from 18 days

Listen to the heartbeat at 21 days

Listen and see the tiny heartbeat at 28 days

Listen to the heartbeat at 11 weeks

• https://archive.org/details/BabysHeartbeatAt11Weeks

Listen to the heartbeat at 13.5 weeks

Taken with a doppler ultrasound

• http://archive.org/details/LilGenghisHeartbeat13Weeks
• http://lilgenghis.blogspot.ie/

Listen to the heartbeat at 17 weeks

Norm and Debra Copeland - This is our baby's heartbeat at 17wks. The random blips are the baby moving!

• https://archive.org/details/NormDebraCopeland_0

Beating heart at 4.5 weeks

Beating heart at 5.5 weeks

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References and Sources

References for heart starting to beat at 21 days

Campbell, 2004 14
Carlson, 2004 430
de Vries and Saunders, 1962 96
Gardner and O'Rahilly, 1976 583
Gilbert-Barness and Debich-Spicer, 1997 650
Gittenger-de Groot et al., 2000 17
Kurjak and Kos, 1994 439
Moore and Persaud, 1998 77
Navaratnam, 1991 147-148
O'Rahilly and Müller, 1987 99
Pansky, 1982 296
van van Heeswijk et al., 1990 153
Heeswijk et al., 1990 151
Wisser and Dirschedl, 1994 108

[1]. F Gary Cunningham, Paul C. MacDonald, Norman F. Grant, et al., Williams Obstetrics, 20th ed. (Stamford: Appleton and Lange, 1997), 30