What is the meaning of follicle size?

TTC: When you are trying to conceive, either through an ovulation induction cycle or through ivf, the infertility specialist will discuss with you your egg follicle sizes. It is known that the follicle has to reach an average diameter of a minimum of 15 mms for the egg within to be mature. We cannot see the egg because it is microscopic size. Therefore, maturation is assumed by the size of the follicle.

For fertility cycles: During fertility treatment cycles re/i specialists use follicle size to determine when the eggs in the ovary are ready to be released with an injection of HCG or to be removed during an ivf procedure. Follicle size during natural cycles (no medication) less important. Typically for insemination and ivf cycles most doctors use a follicle size of 18-22 mm to determine that the egg is ready.