What does celebrating wedding anniversaries and having baby showers have to do with celebrating birthdays? Wedding anniversaries are to celebrate an accomplishment as what celebrations are for. Celebrating the anniversary of one's birth is not an accomplishment. Especially for children.
The day of the actual wedding ceremony there is a celebration/reception. What accomplishment is there for yearly celebrating that day again?
Why do JWs have baby shower celebrations? Isn't that actually a pre-birthday celebration?
(Food, cake, games with friends and family. Gifts for child in mom's belly who is about to be born.)