Prolactin is a hormone produced by the pituitary gland that helps support breast milk production. Levels naturally rise during pregnancy and breastfeeding.

Outside these stages, elevated prolactin may disrupt the hormonal signals that regulate ovulation, making periods irregular or stopping ovulation altogether.

Possible signs include:
• Irregular or absent periods
• Difficulty becoming pregnant
• Milky nipple discharge when not breastfeeding
• Sometimes, no noticeable symptoms

Possible causes include an underactive thyroid, certain medications, and a usually non-cancerous pituitary growth called a prolactinoma. Stress, exercise and nipple stimulation can also temporarily raise prolactin.

One elevated result does not automatically mean infertility. Your healthcare provider may recommend repeat testing and review your symptoms, medications and thyroid function.

Treatment depends on the cause. When needed, appropriate treatment can help restore ovulation.

If your periods are irregular or absent while trying to conceive, ask your healthcare provider whether prolactin testing is appropriate.