If you're in your first trimester and you can't hear your baby's heartbeat, don't worry. Dopplers can't reliably detect a baby's heartbeat until 10 to 12 weeks. Your doctor may try again on your next visit. An ultrasound may give you clearer results.
How does a home fetal doppler work?
Fetal doppler or fetal heart rate monitor is a handheld device which is used to listen to the baby's heartbeat inside the womb of the mother. Each fetal doppler contains a transducer or a probe which sends out short pulses of ultrasound sound waves into the directed area of the body.
How many weeks does a Doppler work?
How Soon Can I Hear the Heartbeat? Although it is possible for a fetal doppler to detect a heart rate as early as 8 to 10 weeks, it's recommended that you wait until 12 weeks. After this time, it will be easier to hear the beat.