Human pregnancy following cryopreservation, thawing and transfer of an eight-cell embryo

Abstract

The widespread use of clomiphene citrate and exogenous gonadotrophins for in vitro fertilization (IVF) in human frequently results in the production of multiple embryos. Replacement of more than two embryos increases pregnancy rate but may result in multiple pregnancies with increased pre- and post-natal abnormality. Preservation of embryos for a limited time allows fewer embryos to be replaced on several different occasions and thus the problems of multiple pregnancy can be minimized, the effectiveness of a single IVF procedure increased and embryo replacement in adverse maternal conditions avoided. Preimplantation embryos have been successfully cryopreserved in many animal species. The sensitivity of embryos to cooling and freezing varies between species and stages of embryo development. We report here the cryopreservation procedures that allow a high survival rate of four- and eight-cell human embryos and the establishment of a pregnancy following the freezing and storage of an eight-cell embryo for 4 months in liquid nitrogen. The pregnancy terminated at 24 weeks' gestation due to development of a septic Streptomyces agalactiae chorion amnionitis after premature membrane rupture.

A closed system supports the developmental competence of human embryos after vitrification

“…Since the first successful pregnancy was achieved by the transfer of a frozen human embryo [29], attempts at controlling the rate of cooling have had varying success [7]. Embryo cryopreservation has recently been progressed by ultra-rapid vitrification, which was originally applied to murine embryos by Rall and Fahy [25].…”

In vitro and in vivo viability of human blastocysts collapsed by laser pulse or osmotic shock prior to vitrification

“…The first pregnancy from cryopreserved human embryos [1] and the birth of the baby [2] have been achieved using conventional slow freezing regimen and early cleaving embryos. Since the last decade, improvement in human embryo culture systems [3] has increased the opportunity for transfer and cryopreservation of blastocysts.…”

Correlation between embryological factors and pregnancy rate: development of an embryo score in a cryopreservation programme

“…Since the early days of embryo cryopreservation [1][2][3], this technique has become an essential part of Assisted Reproduction Techniques (ART) when surplus developing embryos are available, and is now a standard routine procedure with clinical application.…”