<prompt> Changes in the respiratory system in pregnancy:Vital capacity is increasedSubcostal angle remains unchangedTidal volume remains unalteredResidual volume is decreased  <response>: Changes in respiratory system during pregnancy:With the enlargement of the uterus, specially in the later months, there is elevation of the diaphragm by 4 cm.Total lung capacity is reduced by 5 due to this elevation.Breathing becomes diaphragmatic. Total pulmonary resistance is reduced due to progesterone effect.The subcostal angle increases from 68 to 103, the transverse diameter of the chest expands by 2 cm and the chest circumference increases by 57 cm. A state of hyperventilation occurs during pregnancy leading to increase in tidal volume and therefore respiratory minute volume by 40. 