The document discusses the process of puerperium, which is the period following childbirth where the body returns to its pre-pregnant state over approximately 6 weeks. Key changes include the uterus involuting from 1000g to 100g over this time, the return of ovarian function and menstruation between 8-12 weeks (or longer while breastfeeding), and the production and composition of colostrum and breastmilk. Proper breastfeeding and lactation is encouraged for infant health and development during this postpartum period of maternal physiological changes.