Factor number two is the fact that inside the mother we have a higher amount of oxygen than inside the fetus. And so it moves down its concentration and pressure gradient from the mother's side to the fetus side. And finally, we also have the double bore effect. So the fact that carbon dioxide is being pumped is being expelled into the blood of that mother causes the hemoglobin inside this mother's area to basically decrease its affinity for oxygen. And because of that, more oxygen is expelled, is released, and then the oxygen moves into the capillaries of the Corianic villi. And as the concentration of carbon dioxide decreases within the capillaries of that fetus we have less CO2 that can affect hemoglobin's ability to bind to oxygen.