Is there an association between oocyte number and embryo quality? A systematic review and meta-analysis

Belinda G. Vermey, Su Jen Chua, Mohammad Hadi Zafarmand, Rui Wang, Salvatore Longobardi, Evelyn Cottell, Francois Beckers, Ben W. Mol, Christos A. Venetis, Thomas D'Hooghe

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34 Citations (Scopus)


This systematic review and meta-analysis determined the association between aspirated after ovarian stimulation and top/good quality embryos obtained in women undergoing ovarian stimulation for IVF/intracytoplasmic sperm injection (ICSI). MEDLINE, EMBASE, Scopus, CINAHL and Web of Science were searched for English-language publications on top/good-quality embryos at cleavage (day 2/3) and/or blastocyst (day 5/6) developmental stages, up to 18 November 2017. Twenty-eight studies (three prospective and 25 retrospective) reporting data on 291,752 assisted reproductive technology (ART) cycles were considered eligible. We confirmed a strong positive association between oocytes retrieved and top/good-quality day 2/3 embryos (weighted correlation coefficient [rw] = 0.791), day 5/6 embryos (rw = 0.901), metaphase II oocytes (rw = 0.988), oocytes exhibiting two pronuclei (rw = 0.987) and euploid embryos (rw = 0.851); P < 0.001 for all correlations (evaluated in subsets of the 17 studies). Data from 5657 cycles showed that the group with the most oocytes aspirated had the most top/good-quality day 2/3 embryos (pooled standardized mean differences (high [>15] versus low [<4] 1.91, 95% confidence interval [CI] 1.05–2.77, P < 0.0001; high versus medium [4–15] 1.15, 95% CI 0.74–1.55, P < 0.0001; medium versus low 1.41, 95% CI 0.79–2.03, P < 0.0001). Individual participant meta-analysis would enable accurate determination of these associations and other outcomes.

Original languageEnglish
Pages (from-to)751-763
Number of pages13
JournalReproductive BioMedicine Online
Issue number5
Publication statusPublished - Nov 2019


  • Embryo quality
  • Euploid
  • Oocyte number
  • Oocyte yield

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