In the film, the infamously misogynistic Oliver Reed plays a psychotherapist who has developed an experimental technique that allows patients to manifest their negative emotions as physiological changes to their biology. (Heavy) His star pupil, played by Samantha Eggar, takes the process and runs it across the end-zone, using the bad vibes created by her nasty custody battle with leading man Art Hindle to create a small army of mutant pod children.
Side Note: What is up with early Cronenberg and flat, boring heroes? Thankfully that tendency peaked with captain monotone in Scanners.
The mutants, driven by the dark impulses of their fuck-nutty "mother," don terrifying little primary-colored snowsuits (to hide the nutrient sacks fueling them) and do terrible things like beat a kindergarten teacher to death with wooden mallets in front of her class. (I'd hate to have to pay those kids therapy bills.)
As terrifying as that is, nothing can compare to Cronenberg's god awful day-for-night establishing shots.... I mean the climax. Big spoiler ahead.
When the hero finally confronts his estranged wife, she reveals to him the ultimate baby bump: a multitude of tumor like pods growing from her stomach that eventually rupture into little broodlings that she lovingly licks clean. (Gross)