Blastocyst 4cc represents a fully expanded blastocyst, which is of average quality and is not a good quality blastocyst. Blastocysts are generally formed from fertilized eggs after 4-6 days of culture. 4cc blastocysts represent fully expanded blastocysts, while the number of cell mass cells in blastocysts is relatively small, and the trophoblast cells of blastocysts are composed of sparse cells, therefore, blastocysts 4cc are of average quality and do not belong to high-quality embryos, and have poorer developmental potentials, lower success rates, and are not suitable for single-embryo transfers. Generally in clinical practice blastocysts are categorized into four grades, which are grade A, grade B, grade C and grade D. Usually grade A and B are high quality blastocysts, grade C can be transferred, while grade D embryos need to be eliminated, blastocysts 4cc are of average quality, neither good nor bad. If quality embryos are available, single quality embryos can be chosen for transfer, if in the absence of quality embryos, 4cc embryos can be transferred together with non-quality embryos such as 4BC and 4AC to improve the pregnancy rate. Pregnant women should avoid going to populated places with poor air circulation after embryo transfer, and pay attention to observing whether there are obvious abdominal pain, bleeding and other symptoms, and should seek medical attention promptly if there is any abnormality.