Under normal circumstances, the fertilized egg will implant when the endometrium reaches 9mm or more. If the endometrium is already 12mm, the fertilized egg will also implant. It is recommended to check whether the egg is pregnant through blood HCG half a month after intercourse, because once the fertilized egg implants, the trophoblast cells will start to secrete blood HCG, so a blood test will be able to find out whether the egg is pregnant. However, if the endometrium is thin, for example, less than 9mm, it is difficult for the fertilized egg to implant, which may be caused by estrogen deficiency or cavity adhesions, so it is recommended to have a blood test for sex hormone six and, if necessary, a hysteroscopy to rule out the possibility of cavity adhesions. If there are adhesions in the uterus, the adhesions should be separated under hysteroscopy so that there is a chance of pregnancy in the clinic.