IBCLC Maternal Physiology and Anatomy 2 — Questions and Answers
Question 1: Which hormone is primarily responsible for the milk ejection (let-down) reflex?
- Prolactin
- Oxytocin (Correct answer)
- Estrogen
- Progesterone
Correct answer: Oxytocin
Oxytocin, released from the posterior pituitary gland, causes contraction of myoepithelial cells around the alveoli, ejecting milk into the ducts.
The milk ejection reflex is mediated by oxytocin. When the infant suckles, mechanoreceptors in the nipple-areolar complex send signals to the hypothalamus, which stimulates the posterior pituitary to release oxytocin. Oxytocin binds to receptors on myoepithelial cells surrounding the alveoli, causing them to contract.
Question 2: During which stage of lactogenesis does copious milk production begin?
- Lactogenesis I (mid-pregnancy)
- Lactogenesis II (2-5 days postpartum) (Correct answer)
- Lactogenesis III (established lactation)
- Lactation begins immediately at conception
Correct answer: Lactogenesis II (2-5 days postpartum)
Lactogenesis II is triggered by the rapid fall in progesterone after delivery of the placenta.
Lactogenesis II is triggered primarily by the rapid withdrawal of progesterone following delivery of the placenta. This transition typically occurs 30-40 hours postpartum, with mothers perceiving breast fullness between days 2-5. Factors that can delay it include cesarean birth, diabetes, obesity, and retained placental fragments.
Question 3: What is the function of Montgomery's tubercles on the areola?
- They help the infant locate the nipple visually
- They secrete an oily substance that lubricates and protects the nipple and areola (Correct answer)
- They produce milk as supplementary secretory glands
- They have no known function in lactation
Correct answer: They secrete an oily substance that lubricates and protects the nipple and areola
Montgomery's tubercles are modified sebaceous glands that secrete a lipoid fluid that lubricates the areola and has antibacterial properties.
Montgomery glands secrete an oily substance that lubricates and protects the nipple and areolar skin, provides antibacterial protection, and produces volatile compounds that may help guide the newborn to the breast through olfactory cues. It is recommended not to wash the areola with soap.
Question 4: What role does prolactin play in milk production and how does its release pattern relate to feeding frequency?
- Prolactin levels remain constant regardless of feeding frequency
- Prolactin is released in response to nipple stimulation and is highest during nighttime feedings; frequent feeding maintains elevated prolactin levels (Correct answer)
- Prolactin only affects milk production in the first week postpartum
- Prolactin inhibits milk production until estrogen levels rise
Correct answer: Prolactin is released in response to nipple stimulation and is highest during nighttime feedings; frequent feeding maintains elevated prolactin levels
Prolactin is released in response to nipple stimulation, with naturally higher levels at night.
Prolactin has a circadian pattern with naturally higher baseline levels between 2-5 AM. Each feeding episode triggers a surge above baseline. In the early postpartum weeks, frequent feeding maintains elevated prolactin, critical for establishing prolactin receptor sites. As lactation becomes established, the role shifts to local autocrine control through FIL.
Question 5: What structural change occurs in the breast during pregnancy that prepares it for milk production?
- The breast accumulates additional fat tissue only
- Proliferation of alveolar and ductal tissue under the influence of estrogen, progesterone, prolactin, and human placental lactogen (Correct answer)
- The nipple develops new nerve endings
- Breast size determines milk production capacity
Correct answer: Proliferation of alveolar and ductal tissue under the influence of estrogen, progesterone, prolactin, and human placental lactogen
The mammary gland undergoes significant development with proliferation of alveolar lobules and ductal branching.
Mammary development during pregnancy involves extensive proliferation and differentiation driven by multiple hormones. Estrogen stimulates ductal elongation; progesterone promotes alveolar development; prolactin drives differentiation of lactocytes; and human placental lactogen contributes to both ductal and alveolar growth.
Question 6: A mother presents with unilateral breast engorgement 5 days postpartum. The affected breast is warm, firm, and tender but she has no fever. What is the most likely physiology?
- Mastitis requiring antibiotic treatment
- Physiological engorgement due to increased blood flow and milk volume with insufficient drainage of that breast (Correct answer)
- Breast abscess
- Inflammatory breast cancer
Correct answer: Physiological engorgement due to increased blood flow and milk volume with insufficient drainage of that breast
Unilateral engorgement without systemic symptoms indicates physiological engorgement from milk accumulation and vascular congestion.
Physiological engorgement results from milk stasis within the alveoli and ducts combined with vascular and lymphatic congestion. Unilateral presentation suggests one breast is being drained less effectively. Management includes frequent effective milk removal, cold compresses between feedings, and ensuring proper latch.
IBCLC Maternal Physiology and Anatomy 2
Which hormone is primarily responsible for the milk ejection (let-down) reflex?