Which of the following events cause closure of ductus arteriosus in new born: (A) Compression of thorax during delivery, (B) Compression of pulmonary vessels during delivery, (C) Fall in pulmonary arterial pressure, (D) Fall in systemic arterial pressure
Answer is C. Aeration of newborn lung causes rapid replacement of bronchial and alveolar fluid by air, with this compression of pulmonary vasculature is lowered which results in fall in pulmonary arterial blood pressure.
Thus ductus arteriosus closes.