title: Further evidence that culture media affect perinatal outcome: findings after transfer of fresh and cryopreserved embryos.
abstract: BACKGROUND
  We have previously shown that the medium used for culturing IVF embryos affects the birthweight of the resulting newborns. This observation with potentially far-reaching clinical consequences during later life, was made in singletons conceived during the first IVF treatment cycle after the transfer of fresh embryos. In the present study, we hypothesize that in vitro culture of embryos during the first few days of preimplantation development affects perinatal outcome, not only in singletons conceived in all rank order cycles but also in twins and in children born after transfer of frozen embryos. Furthermore, we investigated the effect of culture medium on gestational age (GA) at birth.
  
  
  METHODS
  Oocytes and embryos from consecutive treatment cycles were alternately assigned to culture in either medium from Vitrolife or from Cook. Data on a cohort of 294 live born singletons conceived after fresh transfer during any of a patient's IVF treatment cycles, as well as data of 67 singletons conceived after frozen embryo transfer (FET) and of 88 children of 44 twin pregnancies after fresh transfer were analysed by means of multiple linear regression.
  
  
  RESULTS
  In vitro culture in medium from Cook resulted in singletons after fresh transfer with a lower mean birthweight (adjusted mean difference, 112 g, P= 0.03), and in more singletons with low birthweight (LBW) <2500 g (P= 0.006) and LBW for GA ≥ 37 weeks (P= 0.015), when compared with singletons born after culture in medium from Vitrolife AB. GA at birth was not related to the medium used (adjusted difference, 0.05 weeks, P = 0.83). Among twins in the Cook group, higher inter-twin mean birthweight disparity and birthweight discordance were found. Z-scores after FET were -0.04 (± 0.14) in the Cook group compared with 0.18 (± 0.21) in the Vitrolife group (P> 0.05).
  
  
  CONCLUSIONS
  Our findings support our hypothesis that culture medium influences perinatal outcome of IVF singletons and twins. A similar trend is seen in case of singletons born after FET. GA was not affected by culture medium. These results indicate that in vitro culture might be an important factor explaining the poorer perinatal outcome after assisted reproduction technology (ART). Further research is needed to confirm this culture medium-induced effect in humans and to provide more insight into whether it is caused by epigenetic disturbance of imprinted genes in fetal or placental tissues. Moreover, embryo culture media and their effects need to be investigated thoroughly to select the best embryo culture medium in order to minimize or prevent short-term risks and maybe even long-term disease susceptibility.
authors.affiliation: Department of Obstetrics and Gynaecology, GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands. e.nelissen@mumc.nl
authors.forename: Ewka C
authors.initials: EC
authors.lastname: Nelissen
authors.forename: Aafke P
authors.initials: AP
authors.lastname: Van Montfoort
authors.forename: Edith
authors.initials: E
authors.lastname: Coonen
authors.forename: Josien G
authors.initials: JG
authors.lastname: Derhaag
authors.forename: Joep P
authors.initials: JP
authors.lastname: Geraedts
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Smits
authors.forename: Jolande A
authors.initials: JA
authors.lastname: Land
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Evers
authors.forename: John C
authors.initials: JC
authors.lastname: Dumoulin
mesh_terms: D000328:Adult; D015331:Cohort Studies; D015925:Cryopreservation / Q000379:methods*; D003470:Culture Media; D046149:Embryo Culture Techniques / Q000379:methods*; D004624:Embryo Transfer / Q000379:methods*; D044127:Epigenesis, Genetic; D005260:Female; D005307:Fertilization in Vitro; D020022:Genetic Predisposition to Disease; D018392:Genomic Imprinting; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012044:Regression Analysis; D027724:Reproductive Techniques, Assisted; D016896:Treatment Outcome
chemical_list: D003470:Culture Media