A nurse is caring for a client who is postpartum and asks, "When will my breast milk come in?" Which of the following responses should the nurse make?

Choice A rationale This is an excessively long duration for the mature milk to transition fully. Initial colostrum is present immediately after birth and provides essential antibodies and nutrients. The transitional milk, which signals the "milk coming in," typically begins sooner than 10 days, marking the shift to a larger volume of mature milk via hormonal changes. Choice B rationale A period of 6 to 8 days postpartum is typically longer than the physiological timeframe for the mature milk transition. The secretion of copious milk, often referred to as the milk "coming in," is primarily triggered by the sudden drop in progesterone and the continued high levels of prolactin after the placenta is delivered. Choice C rationale Milk "coming in" within 2 days is typically too soon for most first-time mothers; however, it can occur this quickly for multiparous women. The process requires a few days for the full endocrine shift to occur, specifically the dramatic decrease in the pregnancy-sustaining hormone progesterone, which acts as a mammary gland inhibitor. Choice D rationale The secretion of copious mature milk, commonly referred to as the "milk coming in," generally occurs between 3 to 5 days postpartum for most women. The removal of the placental hormonal inhibition (progesterone) allows the lactogenic hormone prolactin to trigger the mammary alveolar cells to dramatically increase milk production.