title: Cognitive development of singletons born after intracytoplasmic sperm injection compared with in vitro fertilization and natural conception.
abstract: OBJECTIVE
  To investigate cognitive development of singletons conceived by intracytoplasmic sperm injection (ICSI) at 5-8 years of age.
  
  
  METHODS
  Follow-up study.
  
  
  METHODS
  University medical center, assessments between March 2004 and May 2005.
  
  
  METHODS
  Singletons born between June 1996 and December 1999 after ICSI at the Leiden University Medical Center were compared with matched singletons born after IVF and natural conception (NC).
  
  
  METHODS
  Mode of conception.
  
  
  METHODS
  Intelligence quotient (IQ) was measured with the Revised Amsterdam Child Intelligence Test (short form). The investigators were blinded to conception mode.
  
  
  RESULTS
  Singletons conceived by ICSI (n = 83) achieved lower IQ scores than IVF singletons (n = 83) (adjusted mean difference IQ: 3.6 [95% confidence interval (CI) -0.8, 8.0]). After categorizing IQ outcomes (<85, 85-115, >115), no significant difference in the distribution of IQ was found. Singletons conceived by ICSI (n = 86) achieved lower IQ scores than NC singletons (n = 85); the adjusted mean difference varied between 5 and 7 points (5.6 [95% CI 0.9, 10.3]; 7.1 [95% CI 1.7, 12.5]) depending on the covariates included in the model. Adjustment for prematurity did not change the results. Percentages in IQ categories <85, 85-115, and >115 were 12%, 64%, and 24% for ICSI and 6%, 54%, and 40% for NC, respectively.
  
  
  CONCLUSIONS
  In the relatively limited sample investigated, cognitive development among ICSI singletons was lower than among IVF and NC singletons. Infertility factors or unmeasured confounders may play a role.
authors.affiliation: Department of Pediatrics, Neonatal Center, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Knoester
authors.forename: Frans M
authors.initials: FM
authors.lastname: Helmerhorst
authors.forename: Jan P
authors.initials: JP
authors.lastname: Vandenbroucke
authors.forename: Lucette A J
authors.initials: LA
authors.lastname: van der Westerlaken
authors.forename: Frans J
authors.initials: FJ
authors.lastname: Walther
authors.forename: Sylvia
authors.initials: S
authors.lastname: Veen
mesh_terms: D000328:Adult; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D009426:Netherlands; D012044:Regression Analysis; D020554:Sperm Injections, Intracytoplasmic