What is the dominant function of the placenta for a full-term fetus?

The dominant function of the placenta for a full-term fetus is gas exchange, ensuring that oxygen and carbon dioxide are efficiently exchanged between the mother and the fetus. The placenta acts as an interface, allowing oxygen from maternal blood to be delivered to the fetus, while removing carbon dioxide produced by the fetal metabolism.

While nutrient absorption and waste removal are important roles of the placenta, gas exchange is critical for fetal respiration. The fetus relies on the placenta for these functions, particularly as it cannot breathe air in utero. Amniotic fluid production, although significant for fetal development, mainly serves to cushion the fetus and facilitate movement rather than being a primary function of the placenta itself. Thus, the control of gas exchange represents the most essential role of the placenta in supporting the fetus's life and development.