HLA-G and Infertility: The evaluation of sHLA-G levels in the uterine flushing samples from primary and secondary infertile women revealed higher levels of sHLA-G in secondary infertile women (mean ± standard deviation: 4.53 ± 2.78 ng/mL) compared with primary infertile women (0.14 ± 0.31 ng/mL) (p < 0.0001; Student t test) (Figure 1).