Sleeping On Tummy At 20 Weeks Old

My girl will ocassionally flip to her stomach and sleep on her tummy. As I'm aware of SIDS, but she seems to sleep much better on her tummy and deeper in sleep which is great for her brain development. And if I flip her over, she'll wake up and fidget alot and not sleeping peacefully. Should I continue to let her sleep on her tummy if that's the case?