title: Perinatal morbidity after in vitro fertilization is lower with frozen embryo transfer.
abstract: OBJECTIVE
  To study the association of perinatal outcome and IVF transfer type in a group of infertility patients with standardized treatment and similar prognosis.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  University-based infertility center, January 1998 to June 2006.
  
  
  METHODS
  Two hundred eighteen IVF pregnancies after fresh embryo transfer (ET); 122 IVF pregnancies after frozen ET.
  
  
  METHODS
  Assessment of perinatal outcome in fresh versus frozen ET pregnancies.
  
  
  METHODS
  Pregnancy outcomes after fresh versus frozen embryo transfer (ET). Primary outcome was a composite of three events: preterm delivery, intrauterine growth restriction, or low birth weight. Secondary outcomes were subtypes of pregnancy loss. Associations were assessed using multivariate logistic regression.
  
  
  RESULTS
  The final sample included 340 pregnancies: 218 fresh and 122 frozen ETs. Singleton pregnancy was less likely after transfer of fresh embryos (odds ratio [OR] 0.39, 95% confidence interval [CI] 0.23-0.67), and pregnancies after fresh ET were more likely to end in first-trimester loss (OR 1.82, 95% CI 1.05-3.13). Composite adverse outcome after transfer of fresh (44.0%) versus frozen (32.6%) embryos was higher (OR 1.52, 95% CI 0.90-2.56) and was strongly associated with twin gestation (OR 23.82, 95% CI 11.16-50.82).
  
  
  CONCLUSIONS
  Perinatal morbidity is higher in IVF pregnancies conceived after a fresh ET compared with a frozen ET. Although some differences are related to conception with twin gestations, these findings suggest that adverse outcomes may be related to differences in IVF procedures.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, University of Pennsylvania, Philadelphia, Pennsylvania, USA. skalra@obgyn.upenn.edu
authors.forename: Suleena
authors.initials: S
authors.lastname: Kansal Kalra
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Ratcliffe
authors.forename: Lauren
authors.initials: L
authors.lastname: Milman
authors.forename: Clarisa R
authors.initials: CR
authors.lastname: Gracia
authors.forename: Christos
authors.initials: C
authors.lastname: Coutifaris
authors.forename: Kurt T
authors.initials: KT
authors.lastname: Barnhart
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004624:Embryo Transfer / Q000009:adverse effects / Q000379:methods* / Q000706:statistics & numerical data*; D004622:Embryo, Mammalian; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000706:statistics & numerical data; D005615:Freezing; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000453:epidemiology*; D008297:Male; D009017:Morbidity; D010500:Perinatology / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D012189:Retrospective Studies