Rachel Bilson [1]'s baby bump was on display as she went shopping for baby essentials in LA [2] on Monday. The mother-to-be is often spotted with her boyfriend, Hayden Christensen [3], but she flew solo for this outing. Since news of her pregnancy [4] came out in May, Rachel has kept busy. She and Hayden recently returned from a nearly monthlong trip to the Caribbean [5], 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 [6] in photos from the past decade and see if you can tell the difference.