What important function does the placenta serve during pregnancy?

The placenta plays a crucial role during pregnancy by facilitating gas and nutrient exchange between the mother and fetus, which is vital for the development and growth of the fetus. It acts as an interface where oxygen and nutrients from the maternal blood can be transferred to the fetal blood while simultaneously allowing waste products, such as carbon dioxide and metabolic waste from the fetus, to be expelled back into the maternal circulation for disposal.

This function is key in ensuring that the fetus receives everything it needs for proper development while also maintaining an optimal environment. The placenta effectively allows direct blood supply to the fetus without the two bloodstreams mixing, thus protecting the fetus from potential harmful substances while allowing for this essential exchange of nutrients and gases.

The other options do not accurately reflect the primary function of the placenta. For instance, while the placenta provides a degree of protection, it does not act as a barrier to all maternal substances, allowing some beneficial elements through while filtering others. It does not produce eggs for the fetus, as that is the role of the ovaries in the female reproductive system. Maintaining the shape of the uterus is not a primary function of the placenta; rather, the uterus itself provides structure and support during pregnancy.