She was pictured during several episodes of season 3 leading up to the eventual birth of Pebbles. While the word pregnancy was never mentioned once, it was referred to by several "less controversial" (at the time anyway) terms. They even chanced her regular appearance and clothing for the duration of her pregnancy. Very forward thinking for the time. So while I don't have pictures, I assure you it happened. (Speaking of which, show me pictures of you or you never happened!)