Comparative Study to Evaluate the Changes of Pulmonary Function Parameters during Second and Third Trimester of Uncomplicated Pregnancy

Author(s): Supriya Sardar, Indira Ghosh and Ashmita Chakraborty

The present comparative cross-sectional study was conducted to evaluate pulmonary function parameters in the 2nd and 3rd trimesters of pregnancy and compare the results with those of age - and sex - matched normal non - pregnant subjects. Pulmonary function was assessed in terms of FVC, FEV1, FEV1 / FVC, PEFR, MVV, and FEF25 - 75 %. Each group consisted of 25 participants. After obtaining approval from the Institutional Ethical Committee, this study was conducted by the Department of Physiology in association with the Department of Obstetrics and Gynecology of RG Kar Medical College and Hospital from the period of June-2013 to July - 2014. We found that the age of the control subjects was significantly higher than that in the second and third trimesters of pregnancy. Pregnant women's weight and BMI were considerably higher in the third trimester than those in non-pregnant women. The heart rate, systolic blood pressure, and diastolic blood pressure were comparable between the study and control groups. The mean values of PFT parameters such as FVC and PEFR were lower, whereas FEV1, FEV1 / FVC, and FEF25 – 75 % were higher, but there was no statistically significant difference compared to control subjects, except for MVV, which showed a statistically significant decline in the third trimester of pregnancy compared to non - pregnant women. We infer that despite decreasing abdominal compliance, the preservation of FVC is due to increased rib cage volume displacements, relative thoracic cage mobility, and unaffected diaphragmatic motions. Progesterone, corticosteroids, and relaxin compensate for the mechanical disadvantages of the respiratory system caused by pregnancy.

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