Spirometry performance quality and lung function pattern during pregnancy; should testing conditions and interpretation criteria be re-evaluated?

Introduction Despite the prevalence of respiratory disorders in the gravid state, and the crucial role of spirometry in respiratory medicine, its utility for assessing lung function during pregnancy remains infrequent. Putative reasons for this include reservations regarding spirometry performance and its potential influence on test outcomes, although the literature documenting such concerns is insufficient. This study sought to evaluate whether variations in spirometry test performance could impact the diagnosis of pulmonary function patterns throughout gestation. Methods We used spirometry data from a cross-sectional study of 120 pregnant and 114 non-pregnant women who underwent spirometry with uniform instructions given to all subjects. Data were subjected to chi-square testing and subsequently evaluated through logistic regression analysis. Results The acceptable performance rate among pregnant participants was 77.3%, with the most common quality grade being C (37.5%). Pregnant individuals exhibited 2.1 times the odds of achieving a B grade (p=0.037, 95% CI=1.0-4.2) and 4.1 times the odds of achieving an F grade (p=0.02, 95% CI=1.6-9.9) instead of an A grade. Additionally, they manifested 2.9 times the odds of generating unsatisfactory performance (p=0.007, 95% CI=1.3-6.1) compared to non-pregnant participants. Also, pregnant participants displayed 2.5 times the odds of exhibiting a restrictive pattern (p=0.021, 95% CI=1.1-5.7); but pattern classification was not associated with quality grades. Conclusion Despite the higher likelihood of suboptimal spirometry quality, the observed pattern classification remains as expected physiologically, suggesting that spirometry is still a valid tool for assessing lung function in pregnancy.