Where does the primary exchange of oxygen and nutrients occur during pregnancy?

The primary exchange of oxygen and nutrients during pregnancy occurs in the intervillous space of the placenta. This unique area is where maternal blood circulates around the chorionic villi, which contain fetal blood vessels. Oxygen and nutrients diffuse from the maternal blood into the fetal blood through the thin wall of the chorionic villi, while waste products from the fetus move in the opposite direction into the maternal blood for removal.

The intervillous space is crucial for facilitating this exchange because it provides a large surface area and ensures intimate contact between maternal and fetal blood supplies without direct mixing, which safeguards against immunological incompatibilities. This efficient transfer system is essential for the growth and development of the fetus throughout pregnancy.

Understanding this process highlights the significance of the placenta not just as a barrier for waste, but primarily as an organ of exchange that supports fetal health and development.