unsafe to lay on belly in early pregnancy?

I’m only 9 weeks (not showing yet) baby is still super small obviously, and I was laying on my stomach just relaxing, on my phone in the AC, and my boyfriend came in and basically panicked that I am going to hurt the baby for laying on my stomach?… I really don’t think it can in early pregnancy but am I wrong?? i’m sorry if this is a silly question to ask but now i’m curious.. 🥴