Celebrating her 26th birthday in Maui, Nicole Richie also celebrated her new shape, donning a bikini to hit the beach with boyfriend Joel Madden, 28. So how is the notoriously skinny starlet coping with getting big? Though she's been seen working out lightly at an L.A. gym, gaining weight "is what my baby needs," she told Diane Sawyer (when she was four months along, had put on 10 lbs. and was craving spaghetti bolognese for breakfast). "She's never looked better," says a Richie pal. "She's eating healthy," adds another. This week the couple dined at Maui's Seawatch Restaurant. Madden, who says he quit smoking, recently declared, "Our priority is our family and the baby."