First, background.

The overall miscarriage rate is reported as 15-20%, which means 15-20% of recognized pregnancies result in miscarriage. The frequency of spontaneous miscarriage increases further with maternal age. With the development of highly sensitive assays for hCG levels, pregnancies can be detected prior to the expected next period. When these highly sensitive hCG assays are used early, the magnitude of pregnancy loss significantly increases to about 60-70%.

Next, anecdote.

During my first pregnancy, there was a heartbeat detected by ultrasound at 6 weeks. During the seventh week, there was none. Who knows why. I’m a biologist, so I’m guessing some kind of chromosomal abnormality, a nondisjunction, or the like.

Finally: The Point.

A heartbeat doesn’t mean jack 15-20% of the time, maybe 60-70% of the time, if you’re anxious and really want to know if you’re pregnant.