Tryptophan as a biomarker of pregnancy-related immune expression and modulation: an integrative review - Prescott, Stephanie; Billeci, Natasa; Gotcher, Melissa; Patel, Sapna; Almon, Addison; Morgan, Hailey; Abukhalaf, Danielle; Groer, Maureen (Frontiers in Reproductive Health, 2025)