The size of the gestational sac at 28 days after the transfer is around 1.2cm, which is the normal standard. When the transfer is done at the time of ovulation, 28 days after the transfer is equivalent to the size of the gestational sac at around 1.2cm for women with regular menstrual cycle, who have menstruation once a month, and who have their menstrual period at the end of their last menstrual period, that is, at the time of menopause, which is 42 days. If the embryo is well established in the uterine cavity after the transfer, the endometrium has a better internal environment and the embryo receives a better supply of nutrients, the development of the gestational sac may be larger, and vice versa, the development of the gestational sac is slightly smaller. As long as the development of the gestational sac is within the normal range, and the woman does not have lower abdominal pain, vaginal bleeding, blood test blood HCG, progesterone in the normal level, the woman needs to pay attention to appropriate rest, avoid intercourse in early pregnancy, avoid stimulation of undesirable factors, increase the nutrition, and regular checkups can be.