During IVF treatment, our medical staff is often asked by patients, “Several of us had our eggs retrieved on the same day, why were some transferred on the second day, some on the third day, and some on the fifth day?” 1. In most patients, we culture the embryos until the third day, that is, when the fertilized eggs have divided into 8 to 10 cells, and select the best embryos for implantation into the uterus, and then freeze the remaining embryos for preservation; 2. However, in a small number of patients, due to poor ovarian function, only a few eggs are recovered and only one or two embryos are formed. In some patients, the number of eggs recovered is high, but the embryos are not adapted to the external environment, and there are vacuoles and fragments that indicate poor development, so we consider early transfer: Patients with a high number of eggs and good quality embryos, but with a small amount of post-uterine fluid or bloating on the third day that is not suitable for transfer, can culture the embryos until the fifth day, and if the patient’s symptoms improve, the transfer can be performed; then some patients who have received multiple oogenesis embryo transfers without pregnancy can try to transfer blastocysts on the fifth day. The timing of the transfer is not a direct indication of the patient’s chances of getting pregnant, so please follow the advice of the medical professionals and have the transfer at the right time.