What are the chances of having a miscarriage after hearing and seeing the heartbeat?

[Nate1992]

Hello! To start off, the reason I am so concerned is because during the first pregnancy, my wife was diagnosed with a blighted ovum (type of miscarriage; embryo never developed) and miscarried naturally. A month or so later, she found out she was pregnant again which is amazing news for both of us. Due to the blighted ovum, her doctor recommended an early ultrasound to see how the pregnancy was progressing. She believed at the time she was 7 weeks and 2 days pregnant according to her calculations. We went to the ultrasound and thankfully, there was a beautiful, strong heartbeat. Baby measured at 6 weeks 5 days and had a heart rate of 134 BPM. My concern/question, which I have heard stories of this happening, but does anyone know or could anyone help me understand the chances of a miscarriage after hearing the heartbeat? We want nothing more than to have a child and are thankful for this opportunity. If anyone could offer me some advice, I would greatly appreciate it. Thank you in advance and have a great day!