HLA-G and preeclampsia: A number of studies have suggested that a fetal 14bp insertion/deletion polymorphism may account for decreased HLA-G expression and increased preeclampsia risk (O’Brien, et al., 2001; Hylenius et al., 2004; Hviid, et al., 2004; Rokhafrooz, et al., 2018), though other studies have not found the same association (Pabalan, et al., 2015; Nilsson, et al., 2016).