Is it time to shift the attention on early stages embryo development to avoid inconclusive evidence on HPV-related infertility: debate and proposal.

BACKGROUND: Current evidence about in-vivo effects of HPV cannot definitively clarify the possible negative role of this worldwide common infection in early embryo development. However in-vitro evidence, seems to underline a possible negative effect of HPV in increasing blastocyst apoptosis and in reducing the endometrial implantation of trophoblastic cells. On these bases we believe that a new scientific approach is necessary to better understand the real role of male and female HPV infection in infertility and early pregnancy development. METHODS: English literature review of manuscripts focused on HPV infection and human reproduction was conducted. We performed a critical analysis of evidence and possible bias affecting both in-vivo and in-vitro studies regarding this topic. RESULTS: The biggest limitation of the in-vivo studies is due to the inappropriate timing of HPV effects evaluation since evidence about in-vitro studies strongly suggests that a large part of HPV negative effects occurs during a very early stage of embryo development. All the efforts of the scientific community to investigate the real role of HPV in human reproduction disorders cannot underestimate the severe BIAS of actual evidence in postulating new hypothesis and research projects which are fundamental to clarify if HPV may be associated with unexplained couples infertility and early miscarriages. CONCLUSIONS: If the relationship between HPV gametes infection and early human reproduction step impairment will be confirmed, the HPV male and couple vaccination may represent a reliable option to improve fertility in some couples affected by infertility actually classified as "idiopathic" but maybe linked to HPV infection.