FAQ for
The Fly (1986) More at IMDbPro »

Perhaps not. The idea was to mitigate his mutations, not necessarily reverse them, and his unborn child would, he's guessing, provide some sort of extra source of genetic material. Yet he'd also be splicing his genes with the mother, and she still had her clothes - as established in the finale, teleporting with inanimate matter is as bad as teleporting with another living thing. At this stage his mental state has degraded severely, and it's been suggested by the crew that Brundle's plan was a matter of delusion and desperation rather than a worked-through, scientific idea that his "old self" would've concoted.