The required value of progesterone before transfer is less than 2ng/ml and the required value of estradiol is about 48 to 520pg/ml. Before embryo transfer, six tests of reproductive hormones are required, which include progesterone and estradiol level tests. 1. Progesterone: Progesterone should generally be lower than 2ng/ml before transfer, if it is higher than 2ng/ml, it may affect embryo implantation and lead to transfer failure, if the value of progesterone is too high, it needs to be re-adjusted before transfer. Progesterone can promote the endometrium to change to the secretory phase after transplantation, creating an environment for the implantation of fertilized eggs, and also inhibit the contraction of uterine smooth muscle, which is conducive to the development of the fetus. 2. Estradiol: Estradiol should reach 48~520pg/ml before implantation. If estradiol is too low, the thickness of endometrium is not enough which is not favorable for embryo implantation; if estradiol is too high, it will also affect the embryo implantation and over-stimulate the ovaries of pregnant women. Estradiol can thicken the endometrium and increase the uterine glands, as well as promote the blood supply to the endometrium and assist in the maintenance of the uterus to create a suitable environment for embryo implantation. If embryo transfer is required, please consult your doctor in detail and follow the instructions of your doctor.