A fetal heartbeat can typically be detected by ultrasound as early as 5 to 6 weeks of pregnancy. Around this time, cardiac tissue starts to contract, and a heartbeat may be visible using a transvaginal ultrasound, though the heart itself is still developing. By weeks 6 to 7, the heartbeat can be better assessed, and the heart begins to take shape with chambers forming. Usually, the first visible sign of the embryo, known as the fetal pole, appears at 5 to 6 weeks, and cardiac contractions can be seen on ultrasound. However, it may be difficult to detect the heartbeat before week 7. The heartbeat rate generally ranges between 110 to 160 beats per minute as the fetus develops. Hearing the fetal heartbeat with a Doppler device typically occurs later, around 10 to 12 weeks or even as late as 20 to 22 weeks for it to be heard with a standard stethoscope. Ultrasonography remains the earliest and most reliable method to detect fetal cardiac activity in the first trimester. In summary:
- Detection of heartbeat by transvaginal ultrasound: around 5 to 6 weeks (can be difficult before week 7)
- Better assessment of heartbeat by week 6.5 to 7
- Hearing heartbeat by Doppler: generally from 10 to 12 weeks or later
- Audible by stethoscope: around 20 to 22 weeks
This timeline may vary depending on individual factors and the quality of the ultrasound equipment.
