Order a customised baby-themed cake that says, "Congratulations Daddy!" (or "Congratulations Grandma and Grandpa", or whoever you’re announcing the news to) and ask them to open the box to see the extra special sweet treat inside.
Plus, you get to celebrate the good news over some yummy slices of cake and (decaffeinated) tea or coffee too!
This is also a great idea for when you want to do a gender reveal, as you can have the cake on the inside (beneath all the cream or fondant) to be pink or blue, so that when you cut the cake, your eager family members will find out whether you're expecting a girl or a boy.