A baby heart monitor can pick up the baby sounds and the baby heart rate because the heart rate of the baby is faster than the heart rate of the mother and so it is easy to distinguish between the two. You may be able to hear your baby's heart beat for the first time when you're about 8 weeks pregnant if you have an early ultrasound exam, since the baby's heart starts to beat at around 6 weeks. Otherwise, you'll probably hear first hear it with a baby heart monitor at a regular prenatal care visit. Your caregiver may be able to find it with the best heart rate monitor as early as 10 weeks, but it's more common to hear it at 12 weeks. How early the sound can be picked up depends on your baby's position in your uterus, your weight, and the accuracy of your due date.
The baby heart monitor is a handheld ultrasound device that your caregiver can use to find your baby's heartbeat. The monitor sends and receives sound waves that are reflected off your baby's heart. It then processes and amplifies them so you can hear the heartbeat. Many women say that the beating of their baby's tiny heart sounds like the thunder of galloping horses. Hearing it for the first time can be very moving.
The heart rate of a healthy baby in the womb ranges from about 120 to 160 beats per minute, although there is no consensus about the normal fetal heart rate. Current international guidelines recommend for the normal fetal heart rate baseline different ranges of 110 to 150 beats per minute or 110 to 160 bpm. A baby heart beat that's much faster or slower than that may signal a problem. Checking your baby's heartbeat will become a regular part of every prenatal visit.
There is nothing wrong with listening to a baby heart beat using a baby heartbeat monitor at home but they should never be used for reassurance. If a mother is concerned and feels she needs reassurance, she should immediately consult her doctor. It is difficult for an inexperienced person to distinguish between a baby’s heartbeat and the whooshing sounds of a mother’s own pulse or blood flow, and even when parents do find the fetal heartbeat, there is no way for them to know whether the baby is well or in distress. It is for this reason that even the best heart rate monitor should be used as a fun thing or as a way to bond with the baby, not as a reassurance.