Should we look for a low-grade threshold for blastocyst transfer? A scoping review

James M Kemper* (Corresponding Author), Yanhe Liu, Masoud Afnan, Elizabeth R Hammond, Dean E Morbeck, Ben W J Mol

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

15 Citations (Scopus)


Embryo quality is a key determinant of the success of IVF. Although the focus has been on selecting the best embryo for transfer, the classification of low-grade blastocysts (LGB) in existing scoring systems has received less attention. This is worrisome; embryo freezing allows optimal use of all created embryos, thus maximizing the cumulative live birth rate, which is arguably the most important outcome for infertile couples. A PubMed search was conducted in August 2020, using '((('poor-quality' OR 'poor quality') OR ('low-grade' OR 'low grade')) AND ('embryo' OR 'blastocyst')) AND ('pregnancy' OR 'live birth')'. This scoping review shows that LGB have similar euploidy and pregnancy success rates after implantation and have no adverse effects on pregnancy or perinatal outcomes. Evidence for pregnancy outcomes is lacking for different grades of LGB, with most studies clustering all LQB as one to compare with optimal blastocysts.

Original languageEnglish
Pages (from-to)709-716
Number of pages8
JournalReproductive Biomedicine Online
Issue number4
Early online date30 Jan 2021
Publication statusPublished - 1 Apr 2021


  • Blastocyst
  • Embryo transfer
  • Low-grade
  • Quality
  • Threshold


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