Updated by Progyny Clinical Team — May 2025
Prolactin is a hormone that plays a role in fertility by preventing follicle stimulating hormone (FSH) and gonadotropin-releasing hormone (GnRH). These hormones trigger ovulation (when an egg is released from the ovary) and allow eggs to develop and mature.
Why are prolactin levels checked?
People would have their levels tested if they or their partner are having trouble becoming pregnant. A prolactin test measures the amount of the prolactin hormone in the blood. It’s a simple blood test, where a small amount of blood is drawn from an arm vein.
A person with a uterus may also have prolactin levels checked if they have stopped having a period or have any abnormal nipple discharge. It is unclear what role prolactin plays in people with sperm, but abnormal results have been clearly linked to infertility and sex drive.
When are levels checked?
Prolactin levels are checked at any point in the menstrual cycle. Levels vary throughout the day but are highest while sleeping and first thing in the morning. So, if a result is abnormal, the provider may ask patients to repeat the test if the first test was drawn in the afternoon or evening.
Testing levels
High prolactin levels inhibit secretion of FSH, which is the hormone that helps the body prepare for ovulation. So, if prolactin levels are high, ovulation may be suppressed. This is why people who are breastfeeding (and thus have high levels of prolactin) usually don’t become pregnant.
For those who are not breastfeeding, high prolactin levels are often caused by prolactinoma — a small, usually benign, tumor on the pituitary gland that releases excess prolactin in the body. An underactive thyroid can also elevate the prolactin or other, more rare, medical problems can also raise prolactin levels.
Many everyday issues can affect levels too. Intense exercise, lack of sleep, and some foods and medications (especially some anti-depressants and painkillers) can raise prolactin levels. A provider may give out information about how to prepare for the test to minimize the impact of these factors.
Prolactin levels and fertility
If levels are abnormal, it’s important to find out what is causing it and treat it. The solution could be as simple as stopping a specific prescription or could involve treating an underlying condition such as hypothyroidism.
Your fertility provider will work with you to discover and address any underlying problems with the hope of resolving your infertility. The chances of resuming ovulation and subsequent pregnancy are usually excellent if:
- Elevated prolactin levels are brought down.
- The high prolactin level was the cause of a patient’s infertility or subfertility.
If you have questions or concerns, Progyny is here for you. Please contact your Progyny Care Advocate.
Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.