Protamine 2 precursors (Pre-P2), protamine 1 to protamine 2 ratio (P1/P2), and assisted reproduction outcome

ObjectiveTo determine whether the presence of protamine 2 precursors (pre-P2/P2 ratio) and the protamine 1 to protamine 2 ratio (P1/P2) are related to the assisted reproduction outcome.DesignProspective study.SettingAssisted Reproduction Unit and University laboratory.Patient(s)One hundred two infertile patients undergoing treatment at the Assisted Reproduction Unit of the Hospital Clinic of Barcelona.Intervention(s)Intracytoplasmic sperm injection (ICSI) and/or IVF treatment of the infertile patients, sperm protamine analysis through electrophoresis and densitometry, and pre-P2 analysis through Western blot.Main Outcome Measure(s)The presence of protamine 2 precursors (pre-P2/P2 ratio), sperm P1/P2 ratio, fertilization rates by IVF and/or ICSI, and pregnancy outcome.Result(s)Pre-P2/P2 and P1/P2 ratios are positively associated with the pregnancy rate. In addition, the P1/P2 ratio is positively associated with the proportion of embryos obtained by IVF, but not by ICSI. The pre-P2/P2 ratio was not related to the fertilization rate.Conclusion(s)Decreased pre-P2/P2 and P1/P2 ratios are related to a poor pregnancy outcome, but not with the proportion of embryos obtained after ISCI.