How early can the baby's heart beat be heard?

10 weeks at the earliest usually, by 12 weeks for sure. It's harder to hear early on if you've got some extra belly fat or a "deep uterus". They have a little machine that they scan over your pelvis and later when you're further along over your belly and they use a jellyish goo as lube and to help the sound carry. It's easy and painless- unless your dr or nurse is pushing hard trying to find it, then it can be uncomfortable. But really, it's one of the best parts of being pregnant :)