The hormone that tells your ovaries it's time to grow new eggs.
What is Follicle-Stimulating Hormone (FSH)?
FSH is a gonadotropin, a hormone that regulates the function of the ovaries. It is produced by the pituitary gland in the brain and is essentially the "gas pedal" for your reproductive system.
Role in the Menstrual Cycle
Each month, as your period starts, the brain releases FSH to stimulate a group of immature follicles in your ovaries. Think of FSH as the starter pistol for the race to ovulation. It tells these follicles to grow and start produces estrogen.
Why doctors test FSH
FSH levels are a key indicator of ovarian reserve.
- Normal Levels: Indicate the ovaries are responding well to the brain's signals.
- High Levels: If the ovaries are struggling to produce eggs (as in menopause or POI), the brain will pump out more FSH to try and get a response. Chronically high FSH on Day 3 of your cycle indicates your "ovarian gas tank" is getting low.
Medical Disclaimer: All content in this section is for educational and informational purposes only and is NOT intended as medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Bloom is not a replacement for professional medical consultation and should not be used as a primary form of birth control. Read our full Terms of Service.
Modern Fertility Treatment in 2026: Trends & Tech
Read on the go.
Stop scrolling and start syncing. Download the free Bloom app to track FSH (Follicle-Stimulating Hormone) and other key health metrics right on your phone.