Influence of Covid-19 infection on fetal thymus size after recovery

Objectives To investigate the long-term effects of the SARS-CoV-2 infection on the fetal immune system by fetal thymus size measurements with ultrasound (USG). Methods This prospective study was conducted in the Turkish Ministry of Health Ankara City Hospital between November 1, 2020 and April 1, 2021, with recovered, pregnant women, four weeks after they had been confirmed for the SARS-CoV-2 infection by real-time polymerase-chain-reaction (RT-PCR). COVID-19 recovered (CR) pregnant women compared with age-matched pregnant controls in terms of demographic features, fetal thymic-thoracic ratio (TTR), and laboratory parameters. Results There was no difference in demographic features between the two groups. TTR found significantly lower in the CR group than the control group (p=0.001). The fetal TTR showed a significant and moderate correlation with maternal monocyte counts, monocyte to lymphocyte ratio (MLR), and red cell distribution width (RDW); while it did not correlate with lymphocyte counts, c-reactive protein (CRP), and procalcitonin levels. Conclusions The 2019 novel coronavirus disease (COVID-19) reduces fetal thymus size in pregnant women with mild or moderate symptoms after recovery from the infection.