portable crib mattress in pack n play safe?

trossbecky

Does anyone know if it is okay to put in a portable crib mattress with a fitted sheet in the pack and play for baby to sleep on?  Is it safe to have the mattress on there?  We are going to use the pack and play for baby to sleep in in our bedroom at the beginning....just want to make sure it's safe in regard to SIDS; not too soft, etc.  The mattress fits with no gaps, etc. and is only 1 3/4 thick.  

Can anyone advise?  Thanks so much!