Pregnancy and tanning beds

Ok so I know it’s a no no, but I’ve heard of women still using tanning beds while pregnant that was approved by their Dr. I’m sure there was only a certain amount of time you could stay in and go...does anyone have any experience with this at all and have went if your Dr okayed it? I’m just curious ladies...I’m not even pregnant yet but I was wondering about this. I’m sure most women use spray tan if that’s even safe?