Transferring frozen embryos for 30 days with a gestational sac without seeing the fetal heart and buds may be a normal situation, or the embryo may be underdeveloped. 1. Normal situation: As the development of fetal heart and buds is affected by the quality of the embryo and the physical conditions of the mother, the development rate of the embryo is not exactly the same, so it may be a normal situation, and can be reviewed in a week to determine the development of the embryo. 2. Poor embryo development: the transplanted embryo is generally fertilized egg culture 3 days of cleavage embryo or about 5 days of blastocysts, after 30 days of transplantation is equivalent to the level of natural pregnancy 6-7 weeks of gestation, at this time most of the fetal buds can be seen and the fetal heart tube pulsation. If the diameter of the gestational sac in ultrasound examination is >25mm, or the fetal heart and buds are still not seen after 7-10 days, it means that the embryo is more likely to stop. If the pregnant woman checkup found that 30 days after the transfer of frozen embryos with gestational sac did not see fetal heart and fetal buds, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor, improve the relevant examination, clarify the cause of the disease, and symptomatic treatment.