Antral Follicle Count (AFC) – UK Guide

Antral Follicle Count (AFC) is a key ultrasound fertility test. It counts the small follicles developing in the ovaries at the start of a cycle. AFC, together with AMH, helps estimate ovarian reserve and predict how someone may respond to IVF. --- What AFC Measures AFC is the number of follicles measuring 2–10mm seen on an early-cycle ultrasound scan. These follicles may develop into mature eggs later in the cycle. A high or low AFC influences: IVF medication dose Expected number of eggs Stimulation protocol Risk of OHSS (if AFC is high) --- Typical AFC Ranges by Age (General UK Guide) | Age | Typical AFC | |-----|-------------| | 25–30 | 15–30 | | 30–35 | 12–25 | | 35–40 | 6–18 | | 40–45 | 3–10 | | 45+ | <5 | These values vary naturally between individuals. A low AFC does not automatically mean infertility. --- What Low AFC Means Low AFC usually means: Lower expected response to stimulation Fewer eggs in a cycle May need different medication strategies May benefit from mild IVF or dual stimulation However: Success depends more on egg quality, not just quantity Many patients with low AFC have successful outcomes For more on how ovarian reserve affects treatment, see our AMH Test Guide. --- AFC and IVF Success AFC helps clinics: Tailor medication dosages Avoid under- or over-stimulation Choose mild or high-stimulation IVF Estimate how many eggs might be retrieved If you have low