One of five body-swap movies all released around the same time. The others were Big (1988), 18 Again! (1988), Vice Versa (1988) and Dream a Little Dream (1989).
When Chris (Dr. Hammond) is delivering the baby, he picks it up immediately after the birth to reveal that the umbilical cord has already healed, and the baby is perfectly clean and dry.
(Possibly deliberate.) The Hammonds' cat has a male name, "Seymour", but its patches of orange, black and white fur are hallmarks of a calico cat. Virtually all calico cats are female.