This is a multi-center, prospective, observational cohort study, that involves the collection of blood samples from pregnant people during their second trimester of pregnancy. Maternal plasma is isolated from blood samples and subjected to transcriptome and other multi-omic analyses. In conjunction with blood sample collection, extensive clinical data are collected about the pregnancy including any pregnancy complications (e.g., preterm birth, preeclampsia) that may have arisen during pregnancy. Biological markers and clinical data are combined to develop and validate Mirvie's investigational predictive test.