I saw the different conception. Visuddhimagga and Vinayāṭṭhakathā (texts of Theravāda) state that when getting born, a child exhales first, then inhales. Satyasiddhiśastra (text of Sautrantika?) states that the birth starts with out-breath and the life ends with in-breath. By contrast, Abhidharma-mahāvibhāsa and Abhidharmakośabhāsaya (texts of Sarvāstivāda) say there is in-breath at birth and out-breath at death.
Such difference is interesting. Is there a scientist here who clearly knows about this?
Dr @faujidoc1: this is one for you.
The first breath is an indrawing of air to inflate the lungs for the very first time.
The mother’s placenta helps the baby “breathe” while it is growing in the womb. Oxygen and carbon dioxide flow through the blood in the placenta. Most of it goes to the heart and flows through the baby’s body.
At birth, the baby’s lungs are filled with fluid. They are not inflated. The baby takes the first breath within about 10 seconds after delivery. This breath sounds like a gasp, as the newborn’s central nervous system reacts to the sudden change in temperature and environment.
Source : Changes in the newborn at birth: MedlinePlus Medical Encyclopedia
The last breath is an out-flow, after which the person is no longer able to initiate another inbreath.
As the moment of death comes nearer, breathing usually slows down and becomes irregular. It might stop and then start again or there might be long pauses or stops between breaths . This is known as Cheyne-Stokes breathing. This can last for a short time or long time before breathing finally stops.
Source : Last hours of life | Final moments of life