With my first, I was able to find her every single time and listen to her heart. It was a relief. Some night she wouldn’t move, and I could find her heart.

With my second… we had to do heart-monitoring at the doctor’s so I got really good at finding him and he was still really hard to find on the heart-monitor. And he was further out. She was tucked way back, but he was out front, but somehow that made him a lot harder to find.

In my opinion, I’d see if I can find one on something like ebay before spending full price on it. Not every mother will find her baby. And 4 months is pretty early, they recommend trying it 2-3rd trimesters, but most don’t hear anything until 3rd, so you are very unlikely to hear anything for another 2 months.