Bindi Irwin is expecting a baby girl! The 22-year-old mom-to-be announced the sex of her first child with husband Chandler Powell on Instagram with help from one of the residents at the Australia Zoo. "Baby girl, you are our world," she posted. "Our beautiful daughter is now about the same size as a hatchling Aldabra tortoise and is as healthy as can be. We can't wait for her arrival next year." Bindi's younger brother, Robert Irwin, celebrated the news in the comments, gushing, "I can't wait to meet my niece!"