The fetal heartbeat usually begins to be detectable by ultrasound around 5 to 6 weeks of pregnancy. At this time, cardiac tissue starts to contract and may sometimes be seen using a transvaginal ultrasound.
- At 5 to 6 weeks, the heart is starting to form and may show early pulsations.
- By 7 to 8 weeks, the heartbeat is clearer and more consistently observed.
- The fetal heart rate typically ranges from 90-110 beats per minute at 6 to 7 weeks, increasing to 140-170 bpm by the ninth week.
- Sometimes, the heartbeat might not be detected early due to factors like inaccurate dating, body type, or positioning, so if undetected, a follow-up ultrasound in 1-2 weeks is recommended.
- For pregnancies via IVF, fetal heartbeat detection follows a similar timeline counting from embryo transfer, usually visible between the 6th and 7th week after transfer.
In summary, fetal heartbeat is generally first detectable by ultrasound at about 5 to 6 weeks of pregnancy and more reliably seen by 7 to 8 weeks.
