What would you like to do?
What should you say in a congratulations card for a new born baby?
Congratulate them on the arrival of their newborn, and wish them all the best for a long, happy and healthy life together.
Say "Congratulations on the arrival of your baby girl/boy ! I'm glad to hear that you and baby are well. i wish you lots of joy with your baby."
To the parents you can say something along the lines of, "congratulations on bringing this new beautiful life into this world!"
If it's something for the baby you can say, "Welcome to this world little one!"