Arnold Schwarzenegger plays Dr. Alex Hesse, a shy genetic engineer who proves he can carry a baby to term. Ah-nuld’s swollen belly is the joke — the only one — but director Ivan Reitman (Dave) takes it for a few deft spins. The plot is a more fertile ground for comedy than the “sperm milkshake” that made Schwarzenegger and Danny De Vito brothers in Reitman’s Twins.
DeVito shows up in Junior as Dr. Larry Arbogast, Alex’s gynecologist pal, and he and the big guy underplay nicely. Until Alex heads for a birth center in drag, Reitman’s take on the script by Kevin Wade and Chris Conrad is pleasantly low-key. Surprisingly, it is Emma Thompson, on leave from the good manners of Merchant-Ivory (Howards End, The Remains of the Day), who goes barking bonkers. She got her start in comedy, and it’s a kick watching her cut loose. As scientist Diana Reddin, she enters on a runaway cart filled with frozen eggs, one of them her own. It’s the egg that Larry steals to implant in Alex. No fair revealing too much about this bizarre romance — think of it as Emma Thompson’s Frankenstein — but for guys who may be wincing about how a man gives birth, uncross your legs: It’s a C-section.