There are two types of embryos that are transferred for IVF, fresh embryos and embryos that are frozen and stored. These two types of embryos have different HCG levels 14 days after transfer because the time of implantation is different, and also the levels are different for singleton and multiple embryos. For fresh embryos, the normal value of HCG is 200-500u/L after 14 days of singleton transfer, and the normal value of HCG is above 1000u/L after 14 days of multiple embryo transfer. After frozen embryo, it needs to be slowly thawed in the uterine cavity after transfer before it can be laid on the endometrium, this time is longer than that of fresh embryo transfer. 14 days after transfer, the HCG level of singleton is lower, this is a normal situation, the normal value is only 100u/L-200u/L, and the normal value of HCG of multiple embryos is 400u/L.