From The Art and Popular Culture Encyclopedia
Typical for Cronenberg, the film externalises human thought and emotion onto human physiology. In this case, an unconventional psychotherapist (Oliver Reed) has created a technique called "psychoplasmics." He encourages his patients to "go all the way through it" and allow their negative emotions (rage, fear, etc.) to cause their bodies to undergo (usually radical) physical change. A man verbally abused by his father develops welts over his body as a way of expressing his pain. Another patient develops lymphatic cancer, supposedly a manifestation of his self-hatred.
In the case of the principal characters, it causes a woman (Samantha Eggar) to parthenogenetically birth strange, mutated children and, via a telepathic bond, have them act out whatever negative emotions the mother is feeling at the time, with disastrous consequences when her therapist brings those emotions to the surface.
In interviews, Cronenberg has said that this film was partially inspired by a painful custody battle with his ex-wife for their daughter Cassandra (who has since worked as an assistant director on several films, including her father's eXistenZ). Cronenberg has also condemned the censorship of the climactic scene in which Eggar gives birth to one of the monsters and starts tenderly licking it clean. This scene was "trimmed" in the United Kingdom, ironically causing many viewers to assume the character was eating her baby.In 2005, the full uncut version was made available on UK DVD.