The effect of real-time polymerase chain reaction cycle threshold values on perinatal outcomes of pregnant women with COVID-19

Abstract

Objective To evaluate the effect of cycle threshold (Ct) values on the pregnancy outcomes of women with coronavirus disease 2019 (COVID-19). Materials and methods This prospective cohort study was conducted on pregnant women with COVID-19. A real-time polymerase chain reaction (RT-PCR) assay of a nasopharyngeal and oropharyngeal specimen was used for the diagnosis. Initial Ct values for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RT-PCR tests were recorded. 22.9 was the 50th percentile Ct value of the study population. The study population was divided into two groups based on their Ct values: (1) Cases with Higher Ct values (Ct > 22.9)(n = 50) and (2) Cases with lower Ct values (Ct ≤ 22.9)(n = 55). Demographic features, clinical characteristics, disease progression, laboratory test results and pregnancy outcomes were compared between the groups. A receiver operating characteristic (ROC) curve was used to assess the performance of Ct values in predicting obstetric complications. Results Obstetric complication rate was significantly higher in cases with lower Ct values (p < .001). A significantly lower lymphocyte count together with higher ESR, procalcitonin and IL-6 values were observed in the cases with lower Ct values (p > .05). Additionally, a significantly higher NICU admission rate and longer hospital stays were present in the cases with lower Ct values (p > .05). The value in ROC curves with the best balance of sensitivity/specificity was 22.5 (85.7% sensitivity, 63.6% specificity). Conclusion Lower Ct values may be associated with an increased rate of obstetric complications in pregnant women with COVID-19. Physicians should be cautious in the management of cases with Ct levels below 22.5.