You will get to hear your baby's heartbeat for the first time at your second prenatal visit – typically around 12 weeks pregnant.
By pregnancy week 12, your baby's heart is fully developed and growing strong. However, the autonomic nervous system (which regulates the baby's heartbeat) is continuing to develop. The autonomic nervous system is part of your central nervous system and also helps regulate your lungs, intestines, stomach, and various other functions.
At 12 weeks pregnant, your baby's heart rate averages about 167.10 beats per minute. This is pretty fast! But as your little one continues to grow, his or her heartbeat will slow down. The reason for this is the imbalance in his or her autonomic nervous system early in pregnancy.
The autonomic nervous system regulates your baby's heartbeat (also called fetal heart rate), and it works through a balance of two components—the sympathetic nervous system (which regulates your "fight or flight" response and increases your heart rate and blood pressure when it senses "danger" or a threat) and the parasympathetic nervous system (which calms your heartbeat and decreases your blood pressure, allowing you to sit back and relax).
At 12 weeks pregnant, the sympathetic nervous system has more control over your baby's heartbeat, but as the weeks pass, the parasympathetic nervous system will begin to neutralize and balance its partner out.| | Fun Fact:
A normal fetal heart rate is between 110 and 160 beats per minute. A heartbeat outside that range may signal problem. | | |
As a result, your baby's heartbeat will begin to slow down. For example, at week 20 of your pregnancy, the average fetal heart rate is 155 beats per minute, and at week 30, it will decrease to an average of 144 beats per minutes.
During your second prenatal visit at week 12, your doctor will use a Doppler ultrasound to listen to your baby's heartbeat. This is a small, hand-held device that is placed on your belly, and uses sound waves to calculate your baby heartbeat.
A majority of the time, your doctor will be successful in finding your baby's heartbeat. | | Helpful Tip:
Remember to empty your bladder before you have a transvaginal ultrasound. | | |
But because your little one's heart is still very tiny, it may be difficult to find in some circumstances. Don't freak out if this happens. Your doctor can elect to do a transvaginal ultrasound to verify that your baby is doing well and has a heartbeat.
During a transvaginal ultrasound, the transducer (the handheld device that sends and receives ultrasound signals) is inserted into your vagina, instead of sitting on your belly. Because your baby is still small at 12 weeks, transvaginal ultrasounds produce a better image and more accurate reading of your baby's heartbeat.
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