Patients will not have any clinical symptoms on the third day of post-ovulatory conception. Normally, patients may have clinical symptoms only after 7 days of post-ovulatory conception, and significant clinical symptoms will not appear until about 10 days. The main reason is that it takes about a week for the sperm to combine with the egg to form a fertilized egg and for it to be transported through the fallopian tube to the uterine cavity for implantation. Before the fertilized egg implants, the patient’s blood levels of progesterone, chorionic gonadotropin and estrogen do not change, so the patient does not have any clinical symptoms. It is only after about 1-2 days of fertilization that the patient’s blood chorionic gonadotropin, progesterone and estrogen levels rise rapidly, which is why the patient experiences clinical symptoms such as nausea, vomiting, fatigue, drowsiness and breast tenderness.