title: Embryo transfer in days 2 to 4 following intracytoplasmic sperm injection: a prospective cohort study.
abstract: BACKGROUND
  Improvement of assisted reproductive technique (ART) results in higher pregnancy rates from positive Beta HCG to take home baby statistics. Despite developments in culture media allowing blastocyst stage transfer, some centers apply second, third and sometimes fourth day post injection for embryo transfer. This study aimed to compare their reproductive outcomes.
  
  
  METHODS
  This prospective cohort study conducted on 218 infertile couples with at least 4 oocytes retrieved and 2 good quality embryos. They were divided consecutively into 2nd (ET2) or 3rd (ET3) day embryo transfer. Some patients experienced 4rd (ET4) day embryo transfer due to weekend reasons, so we included them in our comparison as well. There were 98, 97 and 23 patients in the aforementioned groups, respectively. Reproductive and pregnancy outcomes were evaluated by Chi square and t-test with the significance level set at α=0.05.
  
  
  RESULTS
  Totally, 73 patients (33%) had positive beta HCG and 39.7 percent of them (n=29) experienced pregnancy loss. Positive Beta HCG was detected in 31(31.6%) of ET2 patients, 38 (39.2%) of ET3 patients and 4 (17.4%) of ET4 group. Abortion or pregnancy loss was reported in 9 (29%) of ET2 patients, 18 (47.4%) of ET3 patients and 2 (50%) of ET4 group.
  
  
  CONCLUSIONS
  Our study demonstrated that there may be a higher pregnancy as well as higher abortion in day 3 embryo transfer.
authors.affiliation: Assistant Professor, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. atossa_mahdavi@yahoo.com , at-mahdavi@tums.ac.ir.
authors.forename: Atossa
authors.initials: A
authors.lastname: Mahdavi
authors.affiliation: Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. qashqaeia@yahoo.com.
authors.forename: Ali
authors.initials: A
authors.lastname: Qashqaei
authors.affiliation: Professor, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. ivf.shariti69@gmail.com.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Aleyasin
authors.affiliation: Professor. Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. ivf.shariti69@gmail.com.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Aghahosseini
authors.affiliation: Assciate Professor, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. safdaria@tums.ac.ir.
authors.forename: Leili
authors.initials: L
authors.lastname: Safdarian
authors.affiliation: Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. zahrarezaeean@yahoo.com.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Rezaeean
authors.affiliation: Embryologist, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. parvin.fallahi@yahoo.com.
authors.forename: Parvin
authors.initials: P
authors.lastname: Fallahi
keywords: Embryo transfer; Infertility; Intracytoplasmic sperm injection; Pregnancy; assisted reproductive technology