airport lax Jennifer Garner stripes

We spotted pregnant Jennifer Garner at LAX on Wednesday, where the 39-year-old channeled her inner child ... and that inner child's name is Harry Potter.

The striped sweater, the big glasses -- all she needs is a lightning scar!

Maybe Jen's testing out Halloween costumes early?

Jen announced her pregnancy about three weeks ago, meaning she's probably almost four months along. The sweater definitely hides her baby bump!