No abstract

After IVF the incidence of MZT is high, with young oocyte age, year of treatment, and extended culture (or embryo stage at transfer) conferring greatest risk. Regarding MZT type, assisted reproductive technology (ART) procedures may influence the timing of embryonic splitting (i.e., division in early embryonic development may be influenced by zona pellucida [ZP] manipulation whereas later splitting may occur during delayed implantation). Poor obstetric/perinatal outcome is significantly impacted by the presence of an "extra" fetus, as high-order multiple gestation concurrent with an MZT conveyed the worst prognosis.

This study was supported by funding provided by Reprogenetics. None of the authors have any competing interests.

This study was supported by institutional funding (Reprogenetics UK and Reprogenetics). DW is supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre Programme. None of the authors have any competing interests.

Preimplantation genetic screening using NGS significantly improves pregnancy outcomes versus PGS using aCGH in STEET cycles. Next-generation sequencing has the ability to identify and screen for embryos with reduced viability such as mosaic embryos and those with partial aneuploidies or triploidy. Pregnancy outcomes with NGS may be improved due to the exclusion of these abnormal embryos.