What is follicle growth? Follicle growth is a condition that affects female fertility. It usually occurs due to an imbalance of hormone levels in a woman\’s body. In the ovary, the size of follicles is usually about 3 to 5 mm. When the size of a follicle exceeds 10 mm, it is considered to be a long follicle. This condition may have some impact on a woman\’s fertility. Diet affects women’s health