When to use baby thank you cards? They are used after your baby is born to show gratitude to those who attended the baby shower or who sent their warm wishes during the pregnancy. Proper etiquette states that inserting a picture of the newborn in the thank you card is expected. Better yet, websites allow you to have the picture become the card itself for the best personal touch. Back in the day, you’d have to deal with a printing press and get charged a lot, but thanks to the boom of the internet, that is not the case anymore.