Respiratory physiology

Hormonal effects cause edema and erythema of the upper airway during pregnancy, which may cause symptoms similar to rhinitis. These effects are important for the physician contemplating endotracheal intubation, as a smaller tube will be required. Some loss of lung capacity may occur as the uterus enlarges, but this is compensated for by widening of the chest diameters. Progesterone stimulates an increase in respiratory drive, causing increased tidal volumes (bigger breaths). Tests of airflow as used in asthma (ie. FeV1) are not affected by pregnancy, although asthma control may change during pregnancy. As the pregnancy progresses, the developing fetus and enlarging uterus require more oxygen and produce more carbon dioxide.

respiratory physiology


Contreras G, Gutierrez M, Berioza T, et al: Ventilatory drive and respiratory function in pregnancy. Am Rev Respir Dis 144:837–841, 1991.

Cugell DW, Frank NR, Gaensler EA: Pulmonary function in pregnancy. I. Serial observations in normal women. Am Rev Tuberc 67:568–597, 1953.

Archer GW, Marx GF. Arterial oxygen tension during apnoea in parturient women. Br J Anaesth 46:358-360, 1974

Lucius H, Gahlenbeck HO, Kleine O, et al: Respiratory functions, buffer system, and electrolyte concentrations of blood during human pregnancy. Respir Physiol 9:311–317, 1970.

Lapinsky SE. Principal author, prepared manuscript. Cardiopulmonary changes in pregnancy: What you need to know. Women’s Health in Primary Care 1999; 2(5):353-363.

Crapo RO: Normal cardiopulmonary physiology during pregnancy. Clin Obstet Gynecol 39:3–16, 1996.

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