how late can heartbeat start in pregnancy

The fetal heartbeat typically starts around 5 to 6 weeks of pregnancy. It can sometimes be detected by ultrasound as early as 5.5 to 6 weeks, but more commonly around 6 to 7 weeks. In some cases, the heartbeat may not be clearly visible until up to 10 weeks, especially depending on the ultrasound type or if there is a miscalculation of pregnancy dating. A late detection of heartbeat (beyond 7-8 weeks) can be due to various reasons including maternal health, baby's health, or dating errors, but it is always important to consult a healthcare provider if there are concerns. So, while the heartbeat usually starts by 6 weeks, it can realistically be detected as late as 8 to 10 weeks in some pregnancies without necessarily indicating a problem.