A longitudinal study of pulmonary function tests during pregnancy.

The study deals with evaluation of pulmonary function status in fifty normal pregnant women tested monthly. The parameters studied were Vital Capacity (VC) Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1st second (FEV1) using Vitalograph Spirometer; tidal volume (VT), inspiratory capacity (IC) and expiratory reserve volume (ERV) using Expirograph and resting minute ventilation (VE) using Tissot's spirometer. Control values were obtained in the same subject 8-10 weeks after delivery. The increase seen in VT, VE and IC was very highly significant. The small increment in frequency of respiration is significant and the declining trend observed in ERV is very highly significant. VC and FVC were maintained by the rise in IC and a concomitant fall in ERV. Rise in VC is attributed mainly to rise in VT than rise in frequency. The results suggest that though pulmonary function is altered during pregnancy, it is not compromised and hence does not induce any mechanical stress on the respiratory efficiency of the pregnant woman.