Fetal Heart Tones

The baby has a heart beat at 6 weeks. By 10-12 weeks the heart tones can be heard in the office. The most common reason for not hearing the heart tones by 12 weeks is that the dates are off.

The baby has a heart beat by 6 weeks. It can usually be seen on ultrasound between 6 and 7weks. Typically the heart beat can be heard in the office between 10-12 weeks. In thin women sometimes the heart beat can heard at 9 weeks. In heavier women it may not be possible to hear the heart beat until 12-14 weeks.

The most common reason for not being able to hear the heart beat in the office is the due date is incorrect. If the fetal heart tones are not audible in the office at 10-12 weeks an ultrasound will usually be ordered to make sure the due date is correct and to see the heart beat. If the doctor cannot hear the heart tones in the office, don’t panic. The due date is probably just off and the baby is not as far along as we thought.

The instrument for hearing the heart beat is a mini ultrasound. It looks like a microphone but is a lot more sophisticated. Microphones that are built to look like the doctor’s instrument can be purchased for $20-$30, don’t waste your money on these as they won’t work. The machines used in the office cost $350 – $800. It is a different technology than the imitation ones sold to expecting parents. If you do use one of these cheaper machines don’t panic if you can’t hear the baby’s heart beat. If you do hear the heart beat with the cheap machines it probably isn’t really the baby.

The gel that is used to hear the heart beats is very safe. It washes out of cloths easily. If some of it gets on your cloths don’t worry it will come out without staining.

One of the most exciting visits is the first time the heart tones are heard. If possible it is great if the women’s partner can be present for that visit. This can be a very exciting time and many people tell me that hearing the heart beat for the first time is when it really sinks in that they are going to have a baby.

Miscarriage occurs in about 15% of all pregnancies. Once the heart beat is seen on ultrasound the miscarriage rate drops to about 5%. When the fetal heart tones are heard in the office the chance of miscarriage drops to about 1%. The first time I am able to hear the baby’s heart beat in the office I like to explain these statistics to my patients and then tease them that it is time to open a college savings plan for the baby.