Each egg in the ovary is contained within a tiny structure called a “follicle”. At any given time, a number of these follicles will be visible by ultrasound. The number of small follicles present in the ovaries at the beginning of a menstrual cycle (antral follicle count) predicts the response of the ovaries to stimulation. An antral follicle count at the onset of a stimulation cycle helps us adjust medication dosing. The antral follicle count complements the CCT as a measure of ovarian reserve.