ONGOING NORMAL-PREGNANCY AFTER TRANSFER OF ZONA-FREE BLASTOCYSTS - IMPLICATIONS FOR EMBRYO-TRANSFER IN THE HUMAN

Recent reports suggest that transfer of day 5 blastocysts improves imp lantation rates in in-vitro fertilization programmes, This paper repor ts a successful ongoing pregnancy after the transfer of zona-free day 6 expanded and hatching blastocysts. The patient was 37 years old and had undergone six stimulated and two thaw cycles previously, all of wh ich had failed, Stimulation was by down-regulation and oocytes recover ed transvaginally by ultrasound guidance. Two pronuclear embryos were co-cultured on Vero cells to day 6, The zonae of two hatching and two fully expanded blastocysts were removed using 0.5% pronase, and the zo na-free blastocysts were then transferred, Pregnancy was confirmed on day 18 with a positive human chorionic gonadotrophin (HCG) and ultraso und at 6 weeks showed a single healthy fetal heart inside a clear sac. At 14 weeks a triple test (oestriol, J-HCG and alpha-fetoprotein) was normal and at 22 weeks a detailed ultrasound scan showed no congenita l anomalies. This is the first report in the human of a normal ongoing pregnancy after the transfer of zona-free day 6 embryos.