What is feeding on the embryo before implantation?

Before implantation, the embryo is nourished primarily through the uterine secretions known as uterine milk and the surrounding endometrial tissue. This phase occurs during the pre-implantation period when the embryo is still a blastocyst, floating in the uterine cavity. The blastocyst absorbs nutrients and fluids from the endometrium, which supports its growth and development until it can establish a more direct connection with the maternal blood supply after implantation.