Follicular phase

The follicular phase runs from the first day of the period until ovulation. FSH stimulates a group of follicles, one usually becomes dominant, and rising oestradiol thickens the endometrium. The length of this phase varies most between people and explains why cycle length differs.

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.