Follicles begin to develop on the 5th day of the menstrual cycle and can mature and rupture on the 14th day of the menstrual cycle and be eliminated. It takes about 14 days for a follicle to mature from the primordial follicle to the mature follicle. The time it takes for a follicle to mature varies from person to person, so it’s best to have regular ultrasounds to see how the follicle is developing. The size of mature follicles is within the range of 18-25mm, follicles that are too small or too large cannot ovulate normally, under normal circumstances, follicles can grow by 2mm per day, if endocrine disorders or abnormal ovarian function will cause follicles to develop in small sizes, and also easy to cause no ovulation, you can draw blood to check the hormone six. It is recommended to use clomiphene and other ovulation stimulating drugs under the guidance of the doctor, the use of ovulation stimulating drugs need regular ultrasound to see the growth of follicles.