Which hormone is responsible for milk ejection after the birth of the baby?

NHM UP Staff Nurse - 2017

Obstetrics & Gynaecology

Easy

Appeared in: NHM UP Staff Nurse - 2017

Explanation

Oxytocin is the primary hormone responsible for the milk ejection or 'let-down' reflex.
It is released from the posterior pituitary gland in a pulsatile fashion in response to the infant's suckling.
Oxytocin stimulates the contraction of myoepithelial cells that surround the alveoli in the mammary glands.
This contraction forces the synthesized milk from the alveoli into the ducts, making it available to the infant.

Option B: Progesterone, along with estrogen, prepares the breasts for lactation during pregnancy but actually inhibits the secretion of milk. Its levels must fall after delivery for lactation to begin.
Option C: Prolactin is responsible for milk production (synthesis) within the alveolar cells of the breast, not milk ejection. While it is essential for lactation, it does not cause the let-down reflex.
Option D: Estrogen's role is similar to progesterone's; it helps in the development of the breast's ductal system during pregnancy but inhibits the actual secretion of milk. Its levels drop significantly after birth, which facilitates the onset of lactation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of lactation, specifically the milk ejection reflex as background academic context rather than a clinical decision trigger.
Nurses play a vital role in educating and supporting new mothers with breastfeeding. Understanding that oxytocin release is key to the let-down reflex helps in providing effective guidance.
The let-down reflex can be inhibited by stress, pain, and anxiety. Nursing interventions should focus on ensuring the mother is comfortable, relaxed, and has adequate pain control to facilitate successful breastfeeding.
What if a mother reports a tingling sensation in her breasts when her baby cries, even before feeding? The nurse should explain that this is a normal and positive sign of the let-down reflex being conditioned to the baby's cues, indicating her body is ready to feed.

How to Approach the Question

This is a factual recall question testing knowledge of endocrine physiology.
First, identify the specific physiological process mentioned in the question, which is 'milk ejection'.
Next, differentiate this process from related but distinct processes like 'milk production' (synthesis) or 'breast development'.
Recall the specific hormones primarily responsible for each of these functions. Prolactin is for production, while Oxytocin is for ejection.
Scan the options to find the hormone that matches the function of milk ejection.
Select Oxytocin as the correct answer, as it is the hormone that causes the contraction of myoepithelial cells for milk let-down.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of lactation, specifically the milk ejection reflex.
Stem keywords: hormone, milk ejection, after birth
Lead-in keywords: Which
Negative lead-in flag: false

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