Low fetal heart rates can often times indicate that there is a problem with your fetus or that it may come out with some kind of defect. However, sometimes children just have low heart rates and they can end up perfectly fine.
Average fetal heart rate is 13-160 beats per minute, if it is lower, this it might mean that your baby is not getting enough oxygen or the heart is weak.
It's not always a problem. The baby's heart beat usually gets stronger in the later stages of pregnancy. If it doesn't there could be a problem. Ask your doctor.
If you are at all concerned that your fetus has a low heart rate, you should see your o.b. immediatley. This probably isn't serious, but it's very important for such situations to be closely monitored by professionals.
If your baby has been diagnosed with a low heart rate then more than likely it will be sent home with a heart monitor. This will let you know by a warning signal of the babies heart rate has dropped below normal.
A slow fetal heart rate is often cause for concern. Your doctor will generally try for a repeat ultrasound in a week to check on development. Although things can turn out fine, a slow heart rate will generally mean a higher a rate of miscarriage.
This is something that is best discussed with your doctor, as any worries you have during pregnancy. Heat rates are most normally taken at the doctors office, ask them if you are concerned.