How common are missed miscarriages?

A

Hi ladies. I’m almost 12 weeks pregnant with my first baby. I got my 10 week scan two weeks ago and my baby looked good with a heartbeat of 159 bpm. However, since my last scan i don’t really feel pregnant anymore. My boobs don’t hurt and my nausea has subsided. I know i should be thankful but I’m worried. Are missed miscarriages common or would i probably know if i miscarried? I haven’t had any severe cramping and I’ve had no bleeding. TIA.