Specifically, compared with the couples in which neither of the spouses carried the allele, those in which both spouses were carriers of the HLA-DQA1*5 allele had a statistically significantly increased probability of high (>50%) HLA-DQA1 compatibility in the total population (65/68 = 95.6% vs. 46/79 = 58.2%, OR = 15.5, 95% CI: 4.5 to 53.7, p<0.001), in the miscarriage group (23/24 = 95.8% vs. 18/37 = 48.6%, OR = 24.3, 95% CI: 3.0 to 198.9, p<0.001), and the IVF-ET failure group (42/44 = 95.5% vs. 28/42 = 66.7%, OR = 10.5, 95% CI: 2.2 to 49.8, p<0.001) (Figure 1). Here, HLA-DQA1 is linked to spontaneous abortion.