Lactational amenorrhoea is defined as the delay in the ovarian cycle due to breastfeeding after childbirth. It serves as a natural, but unreliable form of birth control. During breastfeeding, the sucking of milk by the baby stimulates the pituitary to secrete more prolactin in order to increase milk production. The increased level of prolactin in the blood of the mother may prevent the menstrual cycle by suppressing the release of GnRH (Gonadotropin-Releasing Hormone) which in turn suppresses the production of gonadotropin from the pituitary. Thus lactational amenorrhoea indirectly acts as a natural birth control agent.
