Summary
Prolactin stimulates milk production and oxytocin triggers milk let-down.
In depth
Oestrogen and progesterone build mammary ducts; after birth falling progesterone allows prolactin to trigger milk synthesis. Suckling stimulates oxytocin reflex. Colostrum is rich in antibodies.
Milk composition changes over time. Breast milk supplies antibodies and nutrients. Suckling drives prolactin and oxytocin release.
Example: milk let-down can be triggered by a baby's cry.
The breasts develop during pregnancy under oestrogen (ducts) and progesterone (alveoli), and prolactin from the anterior pituitary prepares milk production. After birth, the fall in progesterone lets prolactin act, and milk is made in the alveoli.
Suckling stimulates nerves that cause oxytocin release, which contracts cells around the alveoli and ejects milk (let-down reflex), while also maintaining prolactin release, so demand adjusts supply. The first milk, colostrum, is rich in antibodies. Breast milk provides nutrients, immune protection and bonding. Lactation can suppress ovulation.
Example: crying of a baby can trigger let-down in the mother.
Key idea: a neuroendocrine reflex with positive feedback for oxytocin and a supply-and-demand loop for prolactin.
Frequently asked questions
What is Lactation?
Prolactin stimulates milk production and oxytocin triggers milk let-down.
Which area of biology covers Lactation, and how advanced is it?
Lactation is one of the 54 topics in Reproduction & Endocrinology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Parturition, Pregnancy Hormones, Hormonal Control of the Menstrual Cycle.
Can you give an example of Lactation?
Breastfeeding may suppress ovulation by inhibiting GnRH.
What should I learn before Lactation?
Work through the Beginner topics in Reproduction & Endocrinology first, such as Reproduction, Asexual Reproduction, Sexual Reproduction, then return to Lactation. Intermediate topics assume the Beginner vocabulary.
What topics are related to Lactation?
The closest topics to Lactation are Parturition, Pregnancy Hormones, Hormonal Control of the Menstrual Cycle, Puberty. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Lactation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Lactation. To practise the whole of Reproduction & Endocrinology, use the Reproduction & Endocrinology quiz.
How is Lactation different from Parturition?
Lactation: Prolactin stimulates milk production and oxytocin triggers milk let-down. Parturition: Positive feedback between oxytocin and uterine contractions drives childbirth. Read both side by side and note what each one explains.
How should I study Lactation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Parturition and explain the difference aloud. Finally, take the Reproduction & Endocrinology quiz and come back to this page for any question you miss.