* Fetal pigs do not breathe air in the womb. They receive oxygen and get rid of carbon dioxide through the placenta, which is connected to the mother's circulatory system.
* The lungs are present and developing but are not functional before birth. While the fetal pig's lungs are forming, they are filled with fluid and do not perform gas exchange.
* The first breath is crucial. After birth, the fetal pig's lungs need to inflate for the first time, allowing them to take in oxygen and expel carbon dioxide on their own.
So, while the lungs are the site of respiration, they don't perform that function until after birth. The placenta takes over the role of gas exchange for the fetal pig while it's developing in the womb.