title: Multiplicity and early gestational age contribute to an increased risk of cerebral palsy from assisted conception: a population-based cohort study.
abstract: BACKGROUND
  This paper assesses the risk of cerebral palsy (CP) in children born after assisted conception compared with children born after natural conception (NC).
  
  
  METHODS
  This population based follow-up study included all 588,967 children born in Denmark from 1995 to 2003. Assisted conception was defined as IVF, with or without ICSI, and ovulation induction (OI), with or without subsequent insemination.
  
  
  RESULTS
  There were 33 139 (5.6%) children born in Denmark from 1995 to 2003 as a result of assisted conception and through to June 2009, 1146 (0.19%) children received a CP diagnosis. Children born after assisted conception had an increased risk of a CP diagnosis, crude hazard rate ratio (HRR) 1.90 (95% CI: 1.57-2.31) compared with NC children. Divided into IVF and OI children compared with NC children, the risk was HRR 2.34 (95% CI: 1.81-3.01) and HRR 1.55 (95% CI: 1.17-2.06), respectively. When we included the intermediate factors multiplicity and gestational age in multivariate models, the risk of CP in assisted conception disappeared. In general, children with CP born after assisted conception had similar CP subtypes and co-morbidities as children with CP born after NC.
  
  
  CONCLUSIONS
  The risk of CP is increased after both IVF and OI. The increased risk of CP in children born after assisted conception, and in particular IVF, is strongly associated with the high proportion of multiplicity and preterm delivery in these pregnancies. A more widespread use of single embryo transfer warrants consideration to enhance the long-term health of children born after IVF.
authors.affiliation: Institute of Public Health, Department of Epidemiology, University of Aarhus, 8000 Arhus, Denmark. dh@soci.au.dk
authors.forename: D
authors.initials: D
authors.lastname: Hvidtjørn
authors.forename: J
authors.initials: J
authors.lastname: Grove
authors.forename: D
authors.initials: D
authors.lastname: Schendel
authors.forename: C
authors.initials: C
authors.lastname: Svaerke
authors.forename: L A
authors.initials: LA
authors.lastname: Schieve
authors.forename: P
authors.initials: P
authors.lastname: Uldall
authors.forename: E
authors.initials: E
authors.lastname: Ernst
authors.forename: B
authors.initials: B
authors.lastname: Jacobsson
authors.forename: P
authors.initials: P
authors.lastname: Thorsen
mesh_terms: D000293:Adolescent; D000328:Adult; D002547:Cerebral Palsy / Q000453:epidemiology*; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005307:Fertilization in Vitro; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D009099:Multiple Birth Offspring; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors