It can be taken as 19mm in diameter, but we need to continue to monitor ovulation in the next two days to see how fast it grows. We know that during the menstrual cycle, after the menstrual period is cleared, the follicle development will be monitored from the 10th day of menstruation. Generally, the follicle development is round or oval, when the follicle grows up to 10mm it is called the dominant follicle, and the dominant follicle usually grows at the rate of 2mm per day, and when it grows up to 19x13mm, it is close to mature follicle, and the mature follicle ranges from 18-25mm, and it may reach the mature follicle, and may continue to grow. Mature follicles range from 18-25mm. It is possible that a follicle may reach maturity at 19 x 13mm, or it may continue to grow. This diameter suggests that the follicle is oval, but an oval follicle does not mean that the egg is abnormal, so this diameter range of the follicle is close to maturity, you need to continue to monitor the follicle to see if it is still growing, and then when it reaches about 20mm, intercourse, it may be more likely to get pregnant.