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Updated June 11, 2014


This hormone is critical for milk ejection. It is secreted by the posterior pituitary (the part of the brain that regulates hormones) and its release is stimulated by seeing or hearing a stimulus, but the most intense release is triggered by suckling. The average pituitary gland contains 6000 mU of oxytocin -- only 50 mU are necessary for the milk ejection reflex. After lactation has been well-established, the first release is within a minute of sucking and continuously releases in spurts. It peaks and levels off about every 6 to 10 minutes during a breastfeed. The hormone goes back to baseline levels within six minutes after nipple stimulation has stopped.

Oxytocin levels are not related to milk volume at all throughout lactation.

Also important to note about oxytocin:

  • This is the same hormone released during labor, which results in uterine contractions.
  • It has peripheral effects. For example, many mothers find that their skin temperature increases while breastfeeding.
  • Breastfeeding moms will find that they're very thirsty. This is related to the increase in plasma (the liquid part of blood) oxytocin levels.
  • This is the same hormone that causes genital contractions during an orgasm.

Keep in mind...

  • Stress and emotional distress may inhibit the let-down reflex and prolactin levels, which will cause there to be less milk available for the baby.
  • Lack of sleep and general exhaustion will inhibit the hormone. Oxytocin levels increase during sleep. Really try to take at least one nap a day!
  • Fear and embarrassment inhibit the milk ejection reflex.
  • Formula supplementation decreases oxytocin levels as there is a lack of stimulation to the breast.


Riordan J, Auerbach KG. Breastfeeding and Human Lactation. Jones and Bartlett. Second Edition.

Lawrence RA. Breastfeeding: A Guide For The Medical Profession. Mosby. Fifth Edition.

Also Known As: "The mothering hormone"

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