Soluble HLA-G is an independent factor for the prediction of pregnancy outcome after ART: a German multi-centre study

background: Soluble HLA-G (sHLA-G) has been suggested as a non-invasive marker for embryo selection to improve pregnancy rates after assisted reproduction technique (ART). Our study aimed at the identification of parameters influencing the detection of sHLA-G in embryo cultures (ECs) and at the prognostic relevance of sHLA-G in a multi-centre study. methods: In total 4212 EC from 2364 cycles were randomly collected from 29 German ART centres and analysed for sHLA-G by Luminex w -based technology. results: Among test and culture conditions, only the cleavage stage of the embryo was identified as an independent factor for sHLA-G detection (P , 0.001). Overall, sHLA-G was significantly associated with pregnancy after ART [P , 0.001; odds ratio: 2.0 (95% CI: 1.7– 2.4)], suggesting that sHLA-G testing might improve the pregnancy rate from 30 to 40%. Importantly, the sHLA-G status of embryos could be associated with pregnancy after single embryo transfer [P ¼ 0.002; odds ratio: 3.3 (95% CI: 1.5 –6.8)] doubling the probability of pregnancy rate to 26% after sHLA-G testing. The patient’s age, number of transferred embryos, morphological grading [EXP(B): 4.3 (95% CI: 2.1– 8.9)] of embryos and sHLA-G status [EXP(B): 2.3 (95% CI: 1.8 –3.1)] were independent predictors of pregnancy, with the latter two being most powerful. conclusions: This study provides significant evidence that the morphological scoring system is still the best strategy for the selection of embryos but that sHLA-G might be considered as a second parameter if a choice has to be made between embryos of morphologically equal quality.