Your baby's heart starts beating around the same time you receive that positive pregnancy test result. Even though the heart beats just five weeks after your last monthly period, you often have to wait a bit longer to hear the heartbeat. Several methods allow you to listen to your baby's heartbeat, and the method you choose depends on precisely and when you get to hear it.
First Trimester Methods
Your doctor's office will use one of two methods to find the baby's heartbeat during the first trimester. A vaginal ultrasound uses a probe that is inserted into the vagina to examine the uterus, placenta and baby. This ultrasound can also show flutters of the baby's beating heart onscreen. An abdominal ultrasound uses a handheld tranducer, which is moved across the abdomen to find the baby and his or her heartbeat.
Second and Third Trimester Technologies
When you're further along in the pregnancy, other technologies can be used to search for the baby's heartbeat. A handheld fetal doppler works as a portable ultrasound unit, without the video technology, that allows health-care providers to listen to the baby's heartbeat and track the heart rate. Additionally, a traditional stethoscope can be placed on the mother's belly to listen to the baby's heartbeat.
Each of these techniques reveal the baby's heartbeat at different times:
- Vaginal ultrasound -- A vaginal ultrasound can show the baby's fluttering heart onscreen and play a simulated recording of the heartbeat as early as 5 to 6 weeks gestation.
- Abdominal ultrasound -- An abdominal ultrasound can pick up the baby's heartbeat during weeks 7 and 8.
- Doppler -- A Doppler can detect the heartbeat at the end of the first trimester and beginning of the second trimester, around 12 to 14 weeks.
- Stethoscope -- Health care providers can use a stethoscope to detect the baby's heartbeat starting at week 22.
Factors Influencing Hearing Heartbeat
In some situations, hearing the baby's heartbeat may be challenging. During early gestation, if you are not as far along in the pregnancy as you think, the baby's heartbeat may not yet be detectable. If using a home doppler device you also may not hear the heartbeat. This could be due to the device being used incorrectly or because you are not as far along in your pregnancy as you thought. If your unborn baby is moving a lot this might make it difficult to find the heartbeat, particularly when a doppler is being used because this device requires an accurate angle and direction.
When typical factors are not preventing your health-care provider from hearing the heartbeat, concerns arise. Several situations warrant medical attention regarding the viability of the pregnancy.
- No heartbeat on a baby measuring larger than 5 mm in the crown to rump length (CRL) -- Health-care providers will likely schedule a repeat ultrasound within a week to look for the heartbeat again and assess the pregnancy's viability.
- No heartbeat on doppler in the second trimester -- An ultrasound will be used to look for the heartbeat should the doppler not find one.
- Lack of movement -- If no heartbeat is coupled with a lack of movement, health-care provides will likely monitor the baby via ultrasound immediately.