Respiratory Physiology Changes During Pregnancy

Physiological Changes

The growing uterus causes upward pressure on the diaphragm, resulting in a decrease in functional residual capacity by approximately 20% during pregnancy, according to the European Respiratory Journal 1
Position matters significantly, and the supine position should be avoided after 20 weeks as the gravid uterus can compress the inferior vena cava, decreasing venous return and cardiac output, as reported by the European Respiratory Journal and Praxis Medical Insights 1, 2

Left lateral positioning optimizes cardiac output, as suggested by Praxis Medical Insights, however a non-Praxis Medical Insights reference is preferred but not available 3