Which hormone is responsible for Milk Ejection after childbirth?

UP CHO - 2018

Obstetrics & Gynaecology

Easy

Appeared in: UP CHO - 2018

Explanation

Oxytocin is the hormone responsible for the milk ejection reflex, also known as the let-down reflex.
It is released from the posterior pituitary gland in response to the infant suckling on the nipple.
Oxytocin acts on the myoepithelial cells surrounding the breast alveoli, causing them to contract and expel the milk into the ducts.
This process is a classic example of a neuroendocrine reflex, initiated by a nerve stimulus (suckling) and completed by a hormonal action (oxytocin).

Option B: Progesterone's primary role during pregnancy is to help develop the breast's lobule-alveolar system. However, it actively inhibits the secretion of milk before birth.
Option C: Prolactin is responsible for milk production (synthesis) in the alveolar cells of the breast. It does not cause the milk to be ejected from the breast.
Option D: Estrogen is responsible for the growth of the breast's ductal system during pregnancy. Like progesterone, high levels of estrogen inhibit the actual secretion of milk.

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 key role in educating and supporting new mothers with breastfeeding. Understanding the difference between milk production (prolactin) and milk ejection (oxytocin) is crucial for troubleshooting breastfeeding issues.
The let-down reflex can be inhibited by psychogenic factors like stress, pain, or anxiety, which suppress oxytocin release. Nurses should promote a calm, supportive environment, pain relief, and skin-to-skin contact to facilitate breastfeeding.
What if? A mother reports her breasts feel full, but the baby is frustrated and not getting any milk. This suggests a problem with the let-down reflex (oxytocin issue), not milk production (prolactin issue). The nursing intervention would focus on relaxation techniques, ensuring a proper latch, and managing pain or anxiety, rather than assuming a low milk supply.

How to Approach the Question

This is a factual recall question from Physiology/Obstetrics.
First, identify the key physiological process in the question stem: 'Milk Ejection'.
Next, differentiate this process from the related but distinct process of 'Milk Production'. Ejection is the release of milk, while production is the synthesis of milk.
Recall the specific hormones associated with each function. Oxytocin is for ejection ('let-down'), and Prolactin is for production.
Evaluate the options. Eliminate hormones that are primarily involved in preparing the breast or inhibiting lactation during pregnancy, such as Estrogen and Progesterone.
Select the option that correctly identifies the hormone for milk ejection.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of lactation, specifically the milk ejection reflex.
Stem keywords: hormone, Milk Ejection, childbirth
Lead-in keywords: Which

QN5WOJJxmEqr6FSDSI2VgO

E6 Physiology Guyton 4SAE Part 3 p. 69-71

E6 Physiology Essentials Sembulingam 10e Part 2 p. 30-32

E6 Obstetrics Williams p. 48-68