The physical process of labour is stimulated by oxytocin in the bloodstream, but the stretching of the cervix and vagina during the birthing process itself triggers an almighty rush of oxytocin in the brain. The resulting delicious cocktail of natural opiates ensures the new mother is primed to bond with her newborn as soon as it enters the world. The act of suckling will bathe her brain in yet more oxytocin, so she basically becomes addicted to caring for her baby.
