The size of a woman’s follicles varies at different times in her menstrual cycle. The size of the follicles is usually detected by doing an ultrasound. If the menstrual cycle is normally normal, small follicles can be found in the ovaries around 3 days of the menstrual cycle, at this time, as long as the body’s hormone levels are normal, the follicles will slowly develop, generally the follicles grow by about 0.2cm per day, to about 14 days to become the dominant follicle, the dominant follicle is generally 1.8-2.2cm in diameter, the mature follicle on the ultrasound is generally round, thin walled, and will appear to protrude to the side of the ovarian surface. The mature follicle is usually round and thin-walled on ultrasound, and also appears to protrude to the side of the ovarian surface with good internal sound transmission. Ovulation usually occurs in about 10 hours. If the follicle is normally ovulated and you are having sex at this time, you have a better chance of getting pregnant. The follicles need a growth cycle and if the follicles are poorly developed, you will not conceive even if they are expelled at this time. There is also a relationship between the speed of follicle development and the number of days of the menstrual cycle, if the menstrual cycle is long, the follicles will develop more slowly at this time. If the menstrual cycle is long, the follicles will develop more slowly. If the menstrual cycle is short, the follicles will develop faster. If you have a 30-day menstrual cycle, you will have a dominant follicle when the follicle reaches 1.0 cm on the 10th day of your period.