A gestational sac of 1.3cm on day 47 of pregnancy is not normal and there may be some individual variation. With the increase of pregnancy weeks and the increase of hormone level in the body, the gestational sac can be seen in the uterine cavity when doing ultrasound examination on the 35th day of menopause. With the increase of pregnancy weeks and the increase of hormone levels, the gestational sac will gradually increase in size, in the 47 days of menopause when the average gestational sac is about 1.7cm, so ultrasound suggests that the gestational sac of 1.3cm is not normal, small. When the ultrasound examination on the 47th day of pregnancy suggests that the gestational sac is 1.3cm, it is necessary to regularly review the ultrasound and HCG, and assess the gestational age again. If the embryo is still underdeveloped even after active treatment, the pregnancy should be terminated at the appropriate time.