(2) In the HLA-A gene sharing between mother and fetus, the gene sharing between mother and fetus in the control group (OR = 0.31,95% CI = 0.10,0.94) was more than that in early-onset preeclampsia group, which suggests that the HLA-A gene sharing between mother and fetus is conducive to the maternal and fetal immune tolerance of pregnancy and protect the fetus from maternal rejection. Here, HLA-A is linked to preeclampsia.