A baby's heartbeat can usually be detected by ultrasound starting around 6 to 7 weeks of pregnancy. At this stage, a vaginal ultrasound can pick up embryonic cardiac activity, which is the early form of a heartbeat. By about 8 to 10 weeks, the heartbeat may become stronger and audible with Doppler during routine prenatal checkups. Hearing the heartbeat with a standard stethoscope typically happens much later, around 20 to 22 weeks of pregnancy.
Details on Timing and Detection Methods
- Embryonic cardiac activity begins around 5 weeks of pregnancy.
- Ultrasound can detect the heartbeat as early as 6 weeks via vaginal ultrasound; abdominal ultrasound is effective around 7 weeks.
- Doppler devices can sometimes pick up the heartbeat from around 8 to 10 weeks.
- The fetal heart is more fully formed by week 10.
- A stethoscope usually detects the heartbeat only after about 20 weeks.
Why Heartbeat Might Not Be Heard Early
- Position of the embryo or baby.
- Type and quality of ultrasound or Doppler device.
- Incorrect dating of the pregnancy.
- Maternal factors such as body type.
Overall, the earliest you can expect to hear a baby's heartbeat with ultrasound is about 6 weeks, with clearer and stronger heartbeats detectable as pregnancy progresses into the first trimester.
