Facebook have added another option in your Life Events within your Timeline, with the option to now add "Expecting a Baby". Life Events are quite simple to add on Facebook.
Life Events can include getting married, buying a new house, a new relationship, the loss of a loved one, and so much more. The "Expecting a Baby" was an addition the social networking giant should've done from day one, but at least its here now.
I didn't even realise I could add that much information through my Life Events until I read the Facebook news myself. You really can have your whole life on Facebook if you choose to! I'm in Australia (if that matters) and I can't choose this option as of yet.