Enormous

Énorme is a movie starring Marina Foïs, Jonathan Cohen, and Jacqueline Kakou. A world traveling pianist and her husband have decided not to have a baby, but then he sees a surprise childbirth on a flight and tampers with her pill.
It takes him suddenly at 40 years: Frédéric wants a baby, Claire never wanted one and they agreed on that. He commits the unforgivable and makes a child behind her back. Claire turns into a whale and Frédéric becomes a doting father.