maternal fetal medicine specialist. The baby's heart starts to beat at around 6 weeks. You may be able to hear – and see – your baby's heart beat for the first time when you're about 8 weeks pregnant if you have an early ultrasound exam.Otherwise, you'll probably first hear it with a fetal Doppler at a regular prenatal care visit.Your caregiver may be able to find it with the Doppler 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.therwise, you'll probably first hear it with a fetal Doppler at a regular prenatal care visit. Your caregiver may be able to find it with the Doppler as early as 10 weeks, but it's more common to hear it at 12 weeks.