Baby announcement cards let the world know about your new bundle of joy. There are two main types of announcement cards: expectant mother cards that let your loved ones know the baby is on their way, and new baby cards announcing the birth. An expectant mother card usually includes the baby's expected due date and other details like a sonogram snapshot. A new baby card, on the other hand, has the baby's full name, details like the time and place of birth, and an invitation for friends and family to come and visit the new arrival.