If the heartbeat sounds remotely atypical, many doctors prescribe a conclusive, and expensive, echocardiogram test.

Ultrasound scans, fetal heart monitors and other devices can't get precise readings of the fetus if the mother carries a lot of additional weight.

A tiny probe in your esophagus takes sound wave pictures of your heart. This form of echocardiogram is called a transesophageal echocardiogram, or TEE.