While an early ultrasound can often detect a heartbeat, it isn’t absolutely necessary in a pregnancy that is progressing properly.
Ultrasounds use sound waves to produce a picture on a screen.
By waiting until 7-8 weeks, it is less likely that a dating error could lead to not detecting the heartbeat in a healthy pregnancy.
Pregnancy dating is only an estimate, and doing an ultrasound just a couple of days too early can mean unnecessary concern and worry about not seeing baby’s heartbeat.
If, based on your last period, you’re 6 weeks along but you ovulated a few days late, it’s possible that the scan was just too early.
Later in pregnancy, genetics takes over your baby’s growth, and your baby will be measured in terms of percentiles.