The first inhale, the last exhale, and the enormous unexamined middle. A human being spends nine months underwater and then, in a single violent second, becomes an air-breathing animal. We tend to picture that first breath as a natural unfolding, the lungs simply beginning what they were built to do. The reality is closer to a demolition. Before birth the lungs are not empty. They are filled with fluid secreted by the lung tissue itself, and that fluid has to go somewhere before air can enter. Labor begins clearing it. The surge of adrenaline and noradrenaline that accompanies delivery flips the epithelial cells lining the airways from secreting fluid to absorbing it, and sodium channels in those cells begin pulling the liquid back into the tissue and the bloodstream. The mechanical compression of the chest during a vaginal delivery squeezes out more. Even so, at the moment of birth the newborn faces a set of collapsed, wet sacs whose internal surfaces are stuck together by the surface tension of water, and it must pull them open with nothing but the muscles of its own chest and diaphragm.

Continue reading → Six Hundred Million Breaths