title: Early embryo cleavage is a strong indicator of embryo quality in human IVF.
abstract: BACKGROUND
  In order to decrease multiple birth rates without decreasing birth rates overall, it is important to increase the capability of selecting the most optimal embryos for transfer. It has been shown that human embryos which cleave early, i.e. complete the first mitotic division within 25-27 h post insemination, provide higher pregnancy and implantation rates.
  
  
  RESULTS
  In this prospective study, an evaluation of 10 798 scored embryos showed that early cleavage resulted in a significantly higher proportion of good quality embryos compared with late cleavage (62.5 versus 33.4%, P < 0.0001). When examining both day 2 and day 3 transfers together, early-cleaving embryos (306 transfers) gave rise to significantly higher rates of pregnancy/transfer (40.5 versus 31.3%, P = 0.0049), implantation (28.0 versus 19.5%, P = 0.0001) and birth/ongoing pregnancy (34.3 versus 24.0%, P = 0.0009) than did late-cleaving embryos (521 transfers). A stepwise logistic regression of all data showed that the total number of good quality embryos and female age were independent predictors of both pregnancies and birth. For intracytoplasmic sperm injection (ICSI) embryos, early cleavage was found to be an independent predictor of birth.
  
  
  CONCLUSIONS
  Early embryo cleavage is a strong biological indicator of embryo potential, and may be used as an additional embryo selection factor for ICSI embryos.
authors.affiliation: Department of Obstetrics and Gynecology, Göteborg University, Sahlgrenska University Hospital, Gothenburg, Sweden. kersti.lundin@medfak.gu.se
authors.forename: K
authors.initials: K
authors.lastname: Lundin
authors.forename: C
authors.initials: C
authors.lastname: Bergh
authors.forename: T
authors.initials: T
authors.lastname: Hardarson
mesh_terms: D000328:Adult; D002970:Cleavage Stage, Ovum; D010064:Embryo Implantation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D016015:Logistic Models; D008297:Male; D008938:Mitosis; D011247:Pregnancy; D011446:Prospective Studies; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors; D016896:Treatment Outcome