The follicle 17mm is able to conceive, usually monitoring ovulation from the beginning of the follicle to develop, about 10mm, with the extension of time, the follicle gradually grows, in the vicinity of ovulation can reach about 18mm, this diameter is also the diameter of the mature follicle. The values are not set in stone and vary greatly from person to person. Follicles are monitored on the ovary from the time they grow, and the size of the follicle may well not match the actual size, so there are small follicles that ovulate, such as a 13-14mm follicle that ovulates, and larger diameters such as follicles that are more than 20mm that ovulate, and it is possible that all of these follicles are mature follicles, and can all become pregnant. 17mm. follicle is very close to the value of a mature follicle and the probability of pregnancy should be higher.