HLA associations and HLA sharing in recurrent miscarriage: A systematic review and meta-analysis

ProblemThe aim of this meta-analysis was to evaluate whether specific maternal HLA alleles and HLA sharing of couples are associated with the occurrence of recurrent miscarriage (RM).Method of studyA systematic literature search was performed for studies that evaluated the association between HLA alleles, HLA sharing and RM. RM was defined as three or more consecutive unexplained miscarriages and a control group was included of women with at least one live birth and no miscarriages in their history. Meta-analyses were performed and the pooled odds ratio (OR) was calculated.ResultsWe included 41 studies. Selection bias was present in 40 studies and information bias in all studies. Meta-analyses showed an increased risk of RM in mothers carrying a HLA-DRB1*4 (OR 1.41, 95% CI 1.05–1.90), HLA-DRB1*15 (OR 1.57, 95% CI 1.15–2.14), or a HLA-E*01:01 allele (OR 1.47, 95% CI 0.20–1.81), and a decreased risk with HLA-DRB1*13 (OR 0.63, 95% CI 0.45–0.89) or HLA-DRB1*14 (OR 0.54, 95% CI 0.31–0.94). Pooling results for HLA sharing showed that HLA-B sharing (OR 1.39, 95% CI 1.11–1.75) and HLA-DR sharing (OR 1.57, 95% CI 1.10–1.25) were both associated with the occurrence of RM.ConclusionAlthough the present systematic review and meta-analysis demonstrates that specific HLA alleles and HLA sharing are associated with RM, a high degree of bias was present and therefore observed results should be interpreted carefully.