Do you mean can you carry a newborn baby in a sling? Sure.
Which one you call the sling???
The one you carry in front you?
I'm thinking about a long, somewhat stretchy cloth that can be tied front or back and holds the baby front or back of the woman. But I am a little at a disadvantage because I didn't really understand your question. What is a baby bag? And why would it make a difference if the baby is a boy or girl?
Lol there known as baby carriers the ones that carry your baby at the front or back and slings are material ones that look like a hammock...with the baby carrier's it varies what age you can use it depending on which one you have but as long as you look up the type you have or are getting on google you should find the age requirements