The embryo implantation rate in assisted reproduction procedures is 20%, which leads to a low clinical pregnancy rate (35%), and even lower live birth rate (25%), per cycle started. Low embryo quality, poor endometrial receptivity, difficulties during the blastocyst hatching process are frequently denoted as the main reasons for the low implantation rate in humans.~The artificial rupture or thinning of the zona pellucida before embryo transfer-assisted hatching (AH)-has been proposed to foster spontaneous hatching and improve embryo implantation rates. Despite great effort, the clinical relevance of AH remains controversial and elusive.~There is a great importance of AH during frozen embryo cycles. Due to previous studies there is no precise answer about the value of AH performed on cryopreserved-thawed embryos. As far as is known, there is no clinical data to indicate the effects of AH on vitrified-warmed embryo transfer.~The objective of this prospective study is to assess the possible impact of assisted hatching on the implantation, pregnancy rate and delivery rate after transfer of vitrified-warmed human embryos.~Eligibility criteria: women age 18-42, cleavage-stage embryo transfer, less than seven IVF cycles with fresh embryo transfer, high quality embryos.~Procedure: mechanical Assisted Hatching~Primary Outcome: delivery rate Secondary Outcome: implantation rate, pregnancy rate and delivery rate.
The objective of study is to assess the possible impact of assisted hatching on the implantation, pregnancy rate and delivery rate after transfer of vitrified-warmed human embryos.