Embryo selection based on the use of morphometric parameters should increase the implantation success rate.

One of the most important issues of "Assisted Reproduction Technologies (ART)" is the possibility of multiple pregnancies which carries a significant risk for maternal-fetal health. These risks can be reduced by restricting the number of embryos transferred.

To do this, it is essential to improve current techniques of embryo selection by developing new tools that would allow the selection of the embryos with higher implantation potential. In previous works (Molina et al 2011) the investigators have demonstrated greater efficacy for the embryo classification systems based on the use of the morphometric variables. The investigators have also developed a profile of embryo implantation using these morphometric variables. In this project the investigators intend to validate the clinical validity of this new embryo classification system by conducting a prospective study of single embryo transfer (SET) in young women at risk of multiple pregnancies.

Inclusion Criteria:

• Personal and family history without interest, not toxic habits.
• Less than 35 years at the time of IVF-ICSI cycle
• Sterility of unknown origin or tubal obstruction.

Exclusion Criteria:

• Repeat nonvoluntary abortions
• Endometriosis
• Polycystic ovary syndrome (criteria Rotterdam 2004)
• Severe male factor (REM <1 million sperm / ml)