Youll probably be pregnant long before the character realizes it. If you go into the "phone" menu and go into the debug screen there. it even shows the preg status.. you can just watch it and it will tell you when the char is preg wayyyyy before it shows any actual state in the game's mechanics. Its pseudo-real until the char first finds it then you later get options to speed things up. Theres not much in the game yet for post-birth.. so dont rush it.