The transfer of two blastocysts is basically a double chorionic twin, and some placental fusion may occur to become a single chorionic twin. Generally speaking, if two blastocysts are transferred in vitro and both of them survive and develop normally, they are usually double chorionic twin, which means that each of the two embryos has a separate placenta and amniotic membrane, i.e., heterozygous twins. In some cases, the placentas of the two embryos may fuse, resulting in a single chorionic villus and double amniotic membrane embryo, but in this case the resulting embryos are still heterozygous twins. In vitro transfer of two blastocysts whether double chorionic double amniotic or single chorionic double amniotic should actively cooperate with the doctor to carry out regular obstetric examination to detect the development of the embryo in the uterus, and if there is any abnormality, it should be timely to consult a doctor for standardized diagnosis and treatment.