L. Criscuoli, R. Rizzo, and B. Fuzzi, Lack of histocompatibility leukocyte antigen-G expression in early embryos is not related to germinal defects or impairment of interleukin-10 production by embryos, Gynecological Endocrinology, vol.20, pp.264-269, 2005.

N. Desai, J. Filipovits, and J. Goldfarb, Secretion of soluble HLA-G by day 3 human embryos associated with higher pregnancy and implantation rates: assay of culture media using a new ELISA kit, Reproductive BioMedicine Online, vol.13, pp.272-277, 2006.

J. D. Fisch, L. Keskintepe, and M. Ginsburg, Graduated embryo score and soluble human leukocyte antigen-G expression improve assisted reproductive technology outcomes and suggest a basis for elective single-embryo transfer, Fertility and Sterility, vol.87, pp.757-763, 2007.

S. Fournel, X. Huc, and M. Aguerre-girr, Comparative reactivity of different HLA-G monoclonal antibodies to soluble HLA-G molecules, Tissue Antigens, vol.55, pp.510-518, 2000.

S. Fournel, M. Aguerre-girr, and A. Campan, Soluble HLA-G: purification from eucaryotic transfected cells and detection by a specific ELISA, American Journal of Reproductive Immunology, vol.42, pp.22-29, 1999.

B. Fuzzi, R. Rizzo, and L. Criscuoli, HLA-G expression in early embryos is a fundamental prerequisite for the obtainment of pregnancy, European Journal of Immunology, vol.32, pp.311-315, 2002.

J. C. Jennings, K. Moreland, and C. M. Peterson, In vitro fertilisation. A review of drug therapy and clinical management, Drugs, vol.52, pp.313-343, 1996.

F. Lesourd, O. Parant, M. Clouet-delannoy, and J. Parinaud, Clinical and biological parameters influencing implantation: score to determine number of embryos to transfer, Reproductive BioMedicine Online, vol.12, pp.453-459, 2006.

Y. Ménézo, K. Elder, and S. Viville, Soluble HLA-G release by the human embryo: an interesting artefact?, Reproductive BioMedicine Online, vol.13, pp.763-764, 2006.

I. Noci, B. Fuzzi, and R. Rizzo, Embryonic soluble HLA-G as a marker of developmental potential in embryos, Human Reproduction, vol.20, pp.138-146, 2005.

V. Rebmann, M. Switala, and I. Eue, Rapid evaluation of soluble HLA-G levels in supernatants of in vitro fertilized embryos, Human Immunology, vol.68, pp.251-258, 2007.

V. Rebmann, J. Lemaoult, and N. Rouas-freiss, Report of the Wet Workshop for Quantification of Soluble HLA-G in Essen, Human Immunology, vol.66, pp.853-863, 2004.

N. Sageshima, T. Shobu, and K. Awai, Soluble HLA-G is absent from human embryo cultures: a reassessment of sHLA-G detection methods, Journal of Reproductive Immunology, vol.75, pp.11-22, 2007.

I. Sargent, A. Swales, and N. Ledee, sHLA-G production by human IVF embryos: can it be measured reliably, Journal of Reproductive Immunology, vol.75, pp.128-132, 2007.

V. R. Shaikly, I. E. Morrison, and M. Taranissi, Analysis of HLA-G in maternal plasma, follicular fluid, and preimplantation embryos reveal an asymmetric pattern of expression, Journal of Immunology, vol.180, pp.4330-4337, 2008.

G. Sher, L. Keskintepe, and . Batzofin, Influence of early ICSI-derived embryo sHLA-G expression on pregnancy and implantation rates: a prospective study, Human Reproduction, vol.20, pp.1359-1363, 2005.

G. Sher, L. Keskintepe, and J. Fisch, Soluble human leukocyte antigen G expression in phase I culture media at 46 h after fertilization predicts pregnancy and implantation from day 3 embryo transfer, Fertility and Sterility, vol.83, pp.1410-1413, 2005.

G. Sher, L. Keskintepe, and M. Nouriani, Expression of sHLA-G in supernatants of individually cultured 46-h embryos: a potentially valuable indicator of 'embryo competency' and IVF outcome, Reproductive Biomedicine Online, vol.9, pp.74-78, 2004.

B. C. Tarlatzis, B. C. Fauser, and E. M. Kolibianakis, GnRH antagonists in ovarian stimulation for IVF, Human Reproduction Update, vol.12, pp.333-340, 2006.

M. J. Van-lierop, F. Wijnands, and Y. W. Loke, Detection of HLA-G by a specific sandwich ELISA using monoclonal antibodies G233 and 56B, Molecular Human Reproduction, vol.8, pp.776-784, 2002.

M. J. Vercammen, A. Verloes, and H. Van-de-velde, Accuracy of soluble human leukocyte antigen-G for predicting pregnancy among women undergoing infertility treatment: meta-analysis, Human Reproduction Update, vol.14, pp.209-218, 2008.

S. M. Yie, H. Balakier, and G. Motamedi, Secretion of human leukocyte antigen-G by human embryos is associated with a higher in vitro fertilization pregnancy rate, Fertility and Sterility, vol.83, pp.30-36, 2005.

, Declaration: The authors report no financial or commercial conflicts of interest