Rachel Bilson's baby bump was on display as she went shopping for baby essentials in LA on Monday. The mother-to-be is often spotted with her boyfriend, Hayden Christensen, but she flew solo for this outing. Since news of her pregnancy came out in May, Rachel has kept busy. She and Hayden recently returned from a nearly monthlong trip to the Caribbean, where she showed off her growing bump in her bikini. Though Rachel has changed a lot since her days on The O.C., one thing always stays the same — the 32-year-old actress is ageless. Try to guess her age in photos from the past decade and see if you can tell the difference.