After the umbilical cord is cut blood ceases to flow through its vessels, and the child has to develop its own system of respiration, digestion and elimination. The physical separation from the mother has been completed and the neonate starts its existence as an anatomically independent individual.
Grof defines the cutting of the umbilical cord as the physiological event that inaugurates the fourth perinatal matrix, marking the decisive anatomical boundary between symbiotic and autonomous existence.
, LSD Psychotherapy: The Healing Potential of Psychedelic Medicine, 1980thesis