A detectable normal heartbeat of the unborn child is essential in a healthy pregnancy. Foetal heartbeat may be detected as early as the sixth week of pregnancy. At 6 weeks the foetal heart beats at around 80 to 100 times a minute. The rate increases almost twofold to 150 to 160 bpm in the next two weeks.
A transvaginal ultra sound can detect foetal heartbeat in its early stages. The heart beats of unborn infants may also be detected with foetal stethoscope or Doppler foetal monitor. The Doppler sound waves reflected off the foetal heart is processed and amplified and heard as a heartbeat.
Between seven and 12 weeks of gestation the foetal heartbeat becomes audible on a heart rate monitor. A lack of a foetal heartbeat thereafter may indicate miscarriage. The miscarriage is confirmed with repeated scanning and serial quantitative beta-HCG.