Large cohort study confirms small added obstetric risk from transfer of longer developed embryos

(European Society of Human Reproduction and Embryology) The transfer of embryos cultured for five or six days (instead of two or three) after fertilisation in IVF and ICSI has become routine in many fertility clinics. Many (but not all) studies show that transferring these longer and better developed embryos - known as blastocysts - will increase the chance of pregnancy and live birth.