reproductive hormones prolactin

The pituitary gland in your brain secretes this hormone in response to eating, mating and ovulation, with its main function being its role in lactation, helping the breasts grow and produce milk for after a baby is born (“Lact” is Latin for milk).


  • Both women AND MEN have small amounts of prolactin in their blood. 
  • Has over 300 functions within the body including reproductive metabolism, immune system and fluid regulation and some behavioural functions.
  • Also produced in the uterus, immune cells, brain, breasts, prostate gland and fat cells.
  • Dopamine and oestrogen regulate prolactin (so stress can play a role!)
  • Too little prolactin is rare, but can cause milk insufficiency and reduced immune response
  • High prolactin levels can disturb the menstrual cycle (also causing galactorrhea, milk discharge from the breasts) and can indicate low libido, vaginal dryness and painful intercourse, and has been often linked to hypothyroidism. If you do experience galactorrhea and not pregnant or breastfeeding don’t be alarmed, as this can be caused by antidepressants, hypertension medication, oral contraceptive or even excessive breast stimulation.

As mentioned above, stress can definitely play a role in this hormone’s levels. Prolactin secreted during stress acts to maintain a balance within the immune system. One study on mice has shown a stress response decreased proinflammatory mediators that improve insulin sensitivity and decrease fat tissue dysfunction. There is also evidence prolactin mediates the effects of chronic stress. Psychology research links prolactin to active coping situations and research shows childhood trauma may predispose women to developing high prolactin levels later in life.

If you’ve been recommended to have your prolactin levels tested, you may want to bear in mind to avoid sex before testing in order for the hormone to register accurately. Ideally the blood should be drawn 3-4 hours after waking, as levels rise during sleep and peak early morning.

Maybe now you’re a PRO in prolactin 😉

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