title: Blastocyst transfer and gender: IVF versus ICSI.
abstract: OBJECTIVE
  To investigate the difference in sex ratio in our centre after day 5 embryo transfer among neonates delivered after fresh in vitro fertilization (IVF), fresh intra cytoplasmatic sperminjection (ICSI) and frozen embryo replacement (FER) compared to expected sex ratio in normal population.
  
  
  METHODS
  Retrospective data after IVF/ICSI/FER therapy from 1995 - 2007 and data from the literature on similar subjects.
  
  
  RESULTS
  Among a total of 420 births after day 5 transfer, there were 225 male and 195 female babies. However, after ICSI alone 30 were female and 21 male. Adding all available data from the literature on gender ratio after long term culture, the ratio of male births to total births (0.545) was significantly (p = 0.004) different from the expected ratio (0.515).
  
  
  CONCLUSIONS
  It appears that significantly more males are born than expected after day 5 transfer in IVF. However, a subgroup analysis in our data comparing IVF, ICSI and FER revealed more females born after ICSI and FER, suggesting that further research is needed in this area.
authors.affiliation: Department of Obstetrics and Gynecology, IVF-unit, University Hospital of Northern Norway, and Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway, martha.agnes.hentemann@unn.no.
authors.forename: Martha Agnes
authors.initials: MA
authors.lastname: Hentemann
authors.forename: Siri
authors.initials: S
authors.lastname: Briskemyr
authors.forename: Kjell
authors.initials: K
authors.lastname: Bertheussen
mesh_terms: D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012744:Sex Ratio; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*