How can an unborn infant in the womb survive without breathing air?

An infant in the womb does not breathe air because its respiratory system is not functional yet. The fetus receives oxygen and nutrients from the mother via the placenta and the umbilical cord. The placenta is an organ that forms in the uterus during pregnancy and connects the mother's blood supply to the fetus's. It allows for the exchange of oxygen, carbon dioxide, and other essential substances between the mother and the fetus.

Before birth, the fetus's lungs are filled with fluid, and it does not take breaths. Instead, the mother's heart pumps oxygenated blood to the placenta, where it enters the fetus's bloodstream through the umbilical vein. The oxygen-rich blood travels to the fetus's heart and is then pumped throughout its body. The carbon dioxide-rich blood from the fetus returns to the placenta through the umbilical arteries, where it enters the mother's bloodstream.

The fetus also receives nutrients from the mother through the placenta. These nutrients help support the fetus's growth and development. The mother's blood also carries away waste products from the fetus, such as carbon dioxide and urea.