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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study received no funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was cleared by Muhimbili University (MUHAS)’s ethical review board, and permission to conduct the study was sought from administrative authorities. A pre-arranged informed consent was signed by all participants. All test procedures were carried out per Helsinki’s declaration. Although spirometry is considered safe during pregnancy (11), safety precautions were taken, including taking a test in a seating position. Potential participants for whom spirometry was contraindicated were excluded from the study. Participants diagnosed with dysfunctional patterns were referred for further evaluation. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data are available up on reasonable request from the author