Q: Perfusing its body by breathing independently instead of utilizing placental oxygen delivered via the umbilical cord is the first challenge of a newborn. At birth, the baby's lungs are filled with lung liquid, which is distinct from amniotic fluid. When the newborn is expelled from the birth canal, its central nervous system reacts to the sudden change in temperature and environment. This triggers it to take the first breath, within about 10 seconds after delivery. With the first breaths, there is a fall in pulmonary vascular resistance, and an increase in the surface area available for gas exchange. Over the next 30 seconds the pulmonary blood flow increases and is oxygenated as it flows through the alveoli of the lungs. Oxygenated blood now reaches the left atrium and ventricle, and through the descending aorta reaches the umbilical arteries. Oxygenated blood now stimulates constriction of the umbilical arteries resulting in a reduction in placental blood flow. As the pulmonary circulation increases there is an equivalent reduction in the placental blood flow which normally ceases completely after about three minutes. These two changes result in a rapid redirection of blood flow into the pulmonary vascular bed, from approximately 4 % to 100 % of cardiac output. The increase in pulmonary venous return results in left atrial pressure being slightly higher than right atrial pressure, which closes the foramen ovale. The flow pattern changes results in a drop in blood flow across the ductus arteriosus and the higher blood oxygen content of blood within the aorta stimulates the constriction and ultimately the closure of this fetal circulatory shunt.\n\nAnswer this question based on the passage: when do babies start breathing on their own? Let's give stream of consciousness first:
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To answer the above question, the relevant sentence is: This triggers it to take the first breath, within about 10 seconds after delivery. Therefore, the final answer is about 10 seconds after delivery.
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