Generally, the fertilized egg will be able to implant in the uterine cavity in 7 to 10 days at the latest, but there are individual differences. When a woman is preparing for pregnancy and has intercourse during ovulation, fertilization occurs within 24 hours of ovulation, and the fertilized egg will move into the uterine cavity and implant in the endometrium, i.e., implantation, 6 to 7 days after fertilization. However, due to the influence of factors such as the speed of movement of the fertilized egg, it can implant in the uterine cavity as late as 7 to 10 days, but there are individual differences. The fertilized egg starts to secrete HCG (human chorionic gonadotropin) one day after it has been laid, so pregnancy can usually be confirmed by testing the HCG level about 10 days after intercourse, and ultrasonography should be performed about 40 days after menopause to clarify a normal intrauterine pregnancy, and to rule out pathological pregnancies such as ectopic pregnancies and hyperemesis gravidarum. Therefore, women with long menstrual cycles can have blood HCG and ultrasound tests under the guidance of a doctor to confirm pregnancy.