In 2014, the Food and Drug Administration (FDA) advised against using fetal dopplers . This is more worrying when it comes to at-home fetal dopplers, because some parents might want to reach for their fetal dopplers every day. Using it for a few minutes once a week shouldn’t cause any harm to your baby.

Description: Doppler Effect works on both light and sound objects. For instance, when a sound object moves towards you, the frequency of the sound waves increases, leading to a higher pitch. Edwin Hubble made the discovery that the universe expands as a consequence of the Doppler Effect.

Not so much. In fact, the US Food and Drug Administration (FDA) has advised against the use of at-home fetal Doppler monitors since 2014, noting that devices used to listen to baby’s heartbeat are legally marketed as “prescription devices” and should be used only by trained operators.

Pregnancy. Some women report feeling a pulse in their stomach when they’re pregnant. While this might feel like your baby’s heartbeat, it’s actually just the pulse in your abdominal aorta.

Of the apps that measure your heart rate for you, our favorite is the popular Instant Heart Rate app, developed by Azumio (iOS and Android, free). We tested the app by comparing its results with manual pulse-taking, and found that it was quite accurate — within a beat or two per minute.

Bellabeat’s Connected System allows pregnant women to listen to their children’s heartbeats through a device that connects to a smartphone with an audio cable. It uses sound waves to find the baby’s heartbeat while the accompanying Bellabeat app records the audio.

Keep in mind that a baby’s heartbeat is much faster than an adult’s. 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 10-12 weeks. Your doctor may try again on your next visit.