Prolactin is produced by the pituitary gland and is best known for driving milk production after childbirth. Its second, less well-known job is suppressing ovulation — the body's built-in way of spacing pregnancies during breastfeeding.
Why it matters outside of breastfeeding
When prolactin rises for any other reason — stress, certain medications, an underactive thyroid, or a small benign pituitary growth — it can suppress ovulation the same way, showing up as a missed or late period, longer cycles, or spotting between periods. Nipple discharge unrelated to pregnancy can also occur, but it's often not the first or only sign.
How it's checked
A simple blood test measures the level, usually repeated on a calm, fasting morning draw if the first result is high, since stress and even the blood draw itself can transiently raise it. What the confirmed number means, and whether it needs treatment, depends on the full clinical picture — never read from the number alone.