When the placental circulation starts?

Placental circulation begins shortly after implantation, around the end of the first week of gestation. As the blastocyst embeds in the uterine wall, trophoblastic cells invade maternal tissues, establishing connections with maternal blood vessels. By the end of the second week, the developing placenta becomes increasingly vascularized, facilitating nutrient and gas exchange between the mother and the embryo. This early circulation is crucial for the embryo's growth and development.