The follicles usually do not get smaller after the chorionic villus test, and if they are found to be smaller, it is necessary to rule out the presence of ovulation symptoms. Chorionic gonadotropin, a glycoprotein hormone produced by the human placenta, can effectively stimulate gonadal activity, thus promoting follicular maturation and ovulation. Injections of human chorionic gonadotropin are generally effective in rapidly promoting follicular maturation, resulting in an increase in follicular size that can be observed on imaging. If the injection of human chorionic gonadotropin results in smaller follicles, it is important to consider whether ovulation occurred during the injection. The expulsion of mature follicles may cause the remaining follicles to become smaller, which is a normal physiologic phenomenon. In a small number of women, follicle size may be caused by follicular atrophy, which requires prompt diagnosis. In addition, women should have regular reproductive checkups after HCG injections.