As others have said, a baby is still a baby. Congratulate your friend on becoming an auntie, ask about hair color/quantity - all the normal things. Pink flowers are always nice for a baby girl - and for mom, too.

Some babies are born with heads full of hair
Some are born bald, but have love to spare
Some are great big, some are wee small
Some have lots of problems, some none at all
Some come in a hurry, some wait a little longer
But all babies have things in common the world over
We love them
We cherish these moments
We rejoice, new love is born
And we are forever changed