If the menstrual cycle is regular and the gestational sac is not visible during the ultrasound examination between 35-40 days of menopause, it is considered that the fertilized egg is late to be implanted. However, the ultrasound can be repeated after 3-5 days. If the gestational sac can be seen and its development is relatively small, it can be determined that ovulation is late and thus, late implantation is the result. When the gestational sac is late and not yet visible in the uterine cavity, it is important to distinguish it from ectopic pregnancy because the gestational sac is also not visible in the uterine cavity. If the gestational sac is late, the pregnancy test will show that the development of the gestational sac is smaller than the time of menopause, and the development of the gestational sac is in accordance with the time of late implantation, which does not correspond to the time of menopause and will be smaller than the time of menopause. However, as long as the fetus is developing normally, there is usually no problem because it is normal to deliver two weeks before and after the expected date of delivery.