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Extracted from Myles Textbook for Midwives 15th Edition. Diane M. Fraser, Margaret A. Cooper (Eds). London; Churchill Livingstone: 2009. Courtesy Elsevier.

Lactation is the term for the production of milk by the breasts to nourish the baby from birth until it is weaned.

During pregnancy oestrogens and progesterone prepare the breast for lactation. Although colostrum is present from the 16th week of pregnancy, production of milk does not occur until after the birth, when placental hormone levels fall, allowing already high levels of prolactin to initiate milk production. Continued production of prolactin is caused by the baby feeding at the breast. Prolactin is involved in the suppression of ovulation and some women remain anovular until lactation ceases.

As lactation progresses, the prolactin response to suckling diminishes and milk removal becomes the driving force behind milk production.

Milk release ' the 'let down' process - is under neuroendocrine control, and is stimulated by the release of oxytocin (see Oxytocin).

Milk production is largely independent of the mother's nutritional status and fluid intake and the practice of encouraging breastfeeding mothers to eat excessively should be abandoned.

Further reading

Medscape (2015). Human milk and lactation. Available at:

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