Physiological Alternation in Small Airway Parameters during Pregnancy: Its application in clinical Scenario.

Abstract

Background : Pregnancy leads to profound alterations in the respiratory system of the mother, leading to alteration in the normal course of common pulmonary diseases. However there is insufficient information regarding the changes in respiratory parameters of smaller airways in different trimesters of pregnancy. Objective : This study was designed to evaluate the pulmonary function tests in 1^st, 2^nd and 3^rd trimesters of pregnancy and compare them with non-pregnant control group. Methods: A cross-sectional study was carried in 200 healthy women in the age range of 19-35 years. The subjects were distributed in four groups, i.e control (non-pregnant) group and 1^st, 2^nd and 3^rdtrimester pregnant groups. Number of subjects in each group is 50. We recorded respiratory parameters in control and study groups. Statistical analysis was done by Z test. Results: There is significant decrease in FEV1, FEV1%, FEF25-75%, FEF25%, FEF50%, FEF75% in all trimesters of pregnancy with maximum decrease in 1^st trimester. Conclusion: The changes in pulmonary function are attributed to major adaptations in the maternal respiratory system and might be due to decline in alveolar Pco₂ caused by hyperventilation which acts as bronchoconstrictor and due to sensitization of respiratory centre due to progesterone. This knowledge of pulmonary function changes during pregnancy may be helpful in the prevention of gestational complications associated with an inadequate maternal respiratory adaptation.