It is understood that the placenta acts as a gateway; an interface between mother and baby. The placenta is a facilitator organ designed to transfer oxygen and nutrients to the baby, therefore it is nutrient rich. It functions similarly to lungs as an exchange/transfer organ and is not a toxic filter, like the liver or kidneys.
The metabolic toxins from the baby are sent back via the placenta to the mother’s liver to be detoxified from her system. The placenta does prevent some toxins from passing through to the baby but they are not stored in the placenta.