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CLC EXAM – CERTIFIED LACTATION COUNSELOR EXAM 2026
QUESTIONS LATEST 2026 – 2027 VERSION SOLVED
QUESTIONS & ANSWERS
CLC EXAM – CERTIFIED LACTATION COUNSELOR
PRACTICE QUESTIONS WITH RATIONALES
SECTION 1: BREAST ANATOMY & PHYSIOLOGY
1. Which hormone is primarily responsible for the milk ejection reflex (let-down)
during breastfeeding?
• A) Prolactin
• B) Estrogen
• C) Oxytocin
• D) Progesterone
Answer: C
Rationale: Oxytocin is the hormone responsible for the milk ejection reflex (let-down),
causing myoepithelial cells surrounding the alveoli to contract and release milk into the
ductal system . Prolactin stimulates milk production, while estrogen and progesterone
support breast development during pregnancy but inhibit lactation until after delivery .
2. The functional milk-secreting units of the breast are the:
• A) Lactiferous sinuses
• B) Ductules
• C) Alveoli (lobules)
• D) Areolar glands
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Answer: C
Rationale: The alveoli are small, grape-like clusters of cells in the breast that synthesize
and secrete milk . Lactiferous ducts transport milk, while Montgomery glands secrete
lubricating oils. Alveoli are the functional units of milk production .
3. Which hormone is primarily responsible for alveolar development during
pregnancy?
• A) Estrogen
• B) Progesterone
• C) Prolactin
• D) Human placental lactogen
Answer: B
Rationale: Progesterone promotes alveolar development and lobuloalveolar
differentiation during pregnancy . Estrogen primarily stimulates ductal growth. Prolactin
is essential for milk synthesis but is inhibited during pregnancy by progesterone.
4. Which hormone inhibits prolactin secretion?
• A) Oxytocin
• B) Estrogen
• C) Dopamine
• D) Progesterone
Answer: C
Rationale: Dopamine (prolactin-inhibiting factor) from the hypothalamus inhibits
prolactin secretion from the anterior pituitary . This is why dopamine-blocking
medications (e.g., antipsychotics) can cause hyperprolactinemia.
5. Which hormone is primarily responsible for milk production (lactogenesis)?
• A) Estrogen
• B) Progesterone
• C) Prolactin
• D) Oxytocin
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Answer: C
Rationale: Prolactin, secreted by the anterior pituitary, stimulates alveolar epithelial
cells (lactocytes) to synthesize milk components . Oxytocin is responsible for milk
ejection. Estrogen and progesterone are involved in breast development during
pregnancy but inhibit milk production.
6. What is the primary function of myoepithelial cells in the breast?
• A) Produce milk
• B) Contract to expel milk
• C) Store milk
• D) Protect the breast from infection
Answer: B
Rationale: Myoepithelial cells surround the alveoli and contract in response to
oxytocin, ejecting milk from the alveoli into the ducts . This contraction is essential for
the milk ejection reflex.
7. Which immunoglobulin is most abundant in human milk?
• A) IgG
• B) IgA (secretory IgA)
• C) IgM
• D) IgE
Answer: B
Rationale: Secretory IgA (sIgA) is the most abundant immunoglobulin in human milk,
providing passive mucosal immunity to the infant . It protects the infant against
pathogens at mucosal surfaces.
8. What is the primary carbohydrate in human milk?
• A) Glucose
• B) Fructose
• C) Lactose
• D) Sucrose
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Answer: C
Rationale: Lactose is the primary carbohydrate in human milk, providing approximately
40% of the calories . It is a disaccharide composed of glucose and galactose and is
essential for infant growth and development.
9. What is the whey-to-casein ratio in mature human milk?
• A) 20:80
• B) 40:60
• C) 60:40
• D) 80:20
Answer: C
Rationale: Mature human milk has a whey-to-casein ratio of approximately 60:40 . This
is in contrast to cow's milk, which has a ratio of approximately 20:80. The higher whey
content makes human milk more easily digestible for infants.
10. What is the protein concentration of human milk highest in?
• A) Colostrum
• B) Transitional milk
• C) Mature milk
• D) Hindmilk
Answer: A
Rationale: Colostrum has the highest protein concentration of any stage of human
milk, containing approximately 2–3 g/dL, largely due to immunoglobulins . Mature milk
contains approximately 0.9–1.2 g/dL.
11. Where does the majority of lymphatic drainage from the breast flow?
• A) Toward the sternum
• B) Toward the axilla (armpit)
• C) Toward the inframammary fold
• D) Toward the clavicle
CLC EXAM – CERTIFIED LACTATION COUNSELOR EXAM 2026
QUESTIONS LATEST 2026 – 2027 VERSION SOLVED
QUESTIONS & ANSWERS
CLC EXAM – CERTIFIED LACTATION COUNSELOR
PRACTICE QUESTIONS WITH RATIONALES
SECTION 1: BREAST ANATOMY & PHYSIOLOGY
1. Which hormone is primarily responsible for the milk ejection reflex (let-down)
during breastfeeding?
• A) Prolactin
• B) Estrogen
• C) Oxytocin
• D) Progesterone
Answer: C
Rationale: Oxytocin is the hormone responsible for the milk ejection reflex (let-down),
causing myoepithelial cells surrounding the alveoli to contract and release milk into the
ductal system . Prolactin stimulates milk production, while estrogen and progesterone
support breast development during pregnancy but inhibit lactation until after delivery .
2. The functional milk-secreting units of the breast are the:
• A) Lactiferous sinuses
• B) Ductules
• C) Alveoli (lobules)
• D) Areolar glands
, Page 2 of 80
Answer: C
Rationale: The alveoli are small, grape-like clusters of cells in the breast that synthesize
and secrete milk . Lactiferous ducts transport milk, while Montgomery glands secrete
lubricating oils. Alveoli are the functional units of milk production .
3. Which hormone is primarily responsible for alveolar development during
pregnancy?
• A) Estrogen
• B) Progesterone
• C) Prolactin
• D) Human placental lactogen
Answer: B
Rationale: Progesterone promotes alveolar development and lobuloalveolar
differentiation during pregnancy . Estrogen primarily stimulates ductal growth. Prolactin
is essential for milk synthesis but is inhibited during pregnancy by progesterone.
4. Which hormone inhibits prolactin secretion?
• A) Oxytocin
• B) Estrogen
• C) Dopamine
• D) Progesterone
Answer: C
Rationale: Dopamine (prolactin-inhibiting factor) from the hypothalamus inhibits
prolactin secretion from the anterior pituitary . This is why dopamine-blocking
medications (e.g., antipsychotics) can cause hyperprolactinemia.
5. Which hormone is primarily responsible for milk production (lactogenesis)?
• A) Estrogen
• B) Progesterone
• C) Prolactin
• D) Oxytocin
, Page 3 of 80
Answer: C
Rationale: Prolactin, secreted by the anterior pituitary, stimulates alveolar epithelial
cells (lactocytes) to synthesize milk components . Oxytocin is responsible for milk
ejection. Estrogen and progesterone are involved in breast development during
pregnancy but inhibit milk production.
6. What is the primary function of myoepithelial cells in the breast?
• A) Produce milk
• B) Contract to expel milk
• C) Store milk
• D) Protect the breast from infection
Answer: B
Rationale: Myoepithelial cells surround the alveoli and contract in response to
oxytocin, ejecting milk from the alveoli into the ducts . This contraction is essential for
the milk ejection reflex.
7. Which immunoglobulin is most abundant in human milk?
• A) IgG
• B) IgA (secretory IgA)
• C) IgM
• D) IgE
Answer: B
Rationale: Secretory IgA (sIgA) is the most abundant immunoglobulin in human milk,
providing passive mucosal immunity to the infant . It protects the infant against
pathogens at mucosal surfaces.
8. What is the primary carbohydrate in human milk?
• A) Glucose
• B) Fructose
• C) Lactose
• D) Sucrose
, Page 4 of 80
Answer: C
Rationale: Lactose is the primary carbohydrate in human milk, providing approximately
40% of the calories . It is a disaccharide composed of glucose and galactose and is
essential for infant growth and development.
9. What is the whey-to-casein ratio in mature human milk?
• A) 20:80
• B) 40:60
• C) 60:40
• D) 80:20
Answer: C
Rationale: Mature human milk has a whey-to-casein ratio of approximately 60:40 . This
is in contrast to cow's milk, which has a ratio of approximately 20:80. The higher whey
content makes human milk more easily digestible for infants.
10. What is the protein concentration of human milk highest in?
• A) Colostrum
• B) Transitional milk
• C) Mature milk
• D) Hindmilk
Answer: A
Rationale: Colostrum has the highest protein concentration of any stage of human
milk, containing approximately 2–3 g/dL, largely due to immunoglobulins . Mature milk
contains approximately 0.9–1.2 g/dL.
11. Where does the majority of lymphatic drainage from the breast flow?
• A) Toward the sternum
• B) Toward the axilla (armpit)
• C) Toward the inframammary fold
• D) Toward the clavicle
