This is further supported by increased levels of immune markers like OPG, which has been associated with COVID-19 severity.65 Similarly, upregulation of VEGFA and MMP-1 is consistent with the upregulation of growth factors and lung injury-related proteinases in the early infection group66, 67 While, most markers increased in the overall analysis showed elevation in either the early or the late gestation exposure group, some markers, including CCL25, MMP-1 OPG, SIRT2, and VEGFA, were not clearly elevated in the smaller, time-stratified analyses. This evidence concerns the gene SIRT2 and COVID-19.