title: Alternative embryo transfer on day 3 or day 5 for reducing the risk of multiple gestations.
abstract: OBJECTIVE
  This study was carried out to reduce the possibility of high-order multiple gestations and the failure of embryo transfer by determining their replacement date based on the number and quality of 2-day embryos.
  
  
  METHODS
  All zygotes were cocultured with cumulus cells in 10 microliters of YS medium containing 10% human follicular fluid (hFF) for 48 or 96 hr. In period I, all embryos were transferred on day 3 (1032 cycles). In period II, the embryos were transferred on either day 3 or day 5 by determining their replacement date based on the number and quality of 2-day embryos: there were 2701 patients in whom embryos were replaced on day 3 (in the case that the number of zygotes was less than eight and the number of good-quality embryos was less than three) and 1952 patients less than 40 years old in whom embryos were replaced on day 5 (in the case that the number of zygotes was eight or more and/or the number of good-quality embryos was three or more). On the other hand, patients who were 40 years old or more were alloted to day 3 transfer cycles, regardless of the number and quality of the 2-day embryos, due to the possibility of their not producing blastocyst-stage embryos in vitro.
  
  
  RESULTS
  The number of embryos transferred in period II was 2.9 +/- 0.6, while that in period I was 3.7 +/- 0.5. The multiple pregnancy rate was significantly decreased in period II (30.7%) compared to that (49.6%) in period I, while the pregnancy and implantation rates in period II (36.1 and 16.4%, respectively) were not lower than those (34.9 and 16.1%, respectively) in period I. The rate of triplet or more gestations was significantly minimized in period II (2.3%) compared to that in period I (26.5%).
  
  
  CONCLUSIONS
  We propose that determination of the date on which embryos should be transferred based on the number and quality of embryos on day 2 may help to maintain an acceptable pregnancy rate, while minimizing embryo transfer failure and high-order multiple gestations.
authors.affiliation: In Vitro Fertilization Laboratory, Maria Women's Hospital, 103-11, Sinseoldong, Dongdaemun-gu, Seoul, Korea. yoonhg@yahoo.com
authors.forename: H G
authors.initials: HG
authors.lastname: Yoon
authors.forename: S H
authors.initials: SH
authors.lastname: Yoon
authors.forename: W Y
authors.initials: WY
authors.lastname: Son
authors.forename: J G
authors.initials: JG
authors.lastname: Kim
authors.forename: K S
authors.initials: KS
authors.lastname: Im
authors.forename: J H
authors.initials: JH
authors.lastname: Lim
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D018920:Coculture Techniques; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D015571:Follicular Fluid / Q000378:metabolism; D006801:Humans; D007246:Infertility / Q000628:therapy; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D012099:Reproductive Techniques; D013997:Time Factors