No one knew Barbara Palvin was pregnant at the Nice Airport on May 13. She waited for her first Cannes Film Festival gown the next day to reveal her baby bump. Fans should've known, though. She dressed herself in a travel outfit worthy of a cool mom 's closet: a bump-concealing trench coat and low-top sneakers. Thankfully, Palvin's not too far along in her first pregnancy—otherwise the 13-hour flight might've grounded her French airport outfit . Paparazzi spotted her outside baggage claim, dressed in L.A. cool-girl essentials. The mom-to-be's cover might've been blown if not for her camel-colored trench coat. The slightly oversize style featured traditional lapels and a few undone buttons, but no belt. She closed its single-breasted bodice herself, hiding a white, pinstripe button-down underneath. Baggy, chocolate-brown trousers emerged from beneath the trench's calf-grazing hem. Then, Palvin traded mom-approved sneaker trends like Puma Speedcats or New Balances for a Converse-coded pair from Autry.…