Pulmonary ventilation in pregnancy.

Serial tests of ventilatory function were made in 38 normal primigravidae during and after pregnancy. During pregnancy all patients showed major changes in tidal volume, functional residual capacity and residual volume. Minor changes were found in many other measurements, all of which occurred at an early stage of pregnancy. Most of the obvious alterations cannot be accounted for adequately by mechanical disturbance from the gravid uterus.