Might be a stupid ?...

This might sound beyond stupid..

But me and SO are about to be first time parents.. and we were washing all the baby stuff and we both wondered why do all the swaddles all have a hole in the back? I was wondering if it’s there to check babies diaper a little? I’m so sorry if I sound like a complete idiot right now! I have no one else to ask.. were the first parents in our group of friends/family and our parents are far away..