title: Biological sex and the risk of cerebral palsy in Victoria, Australia.
abstract: OBJECTIVE
  Males typically outnumber females in cerebral palsy (CP) cohorts. To better understand this 'male disadvantage' and provide insight into causal pathways to CP, this study used 1983 to 2009 Australian CP and population birth cohorts to identify associations and trends with respect to biological sex and CP.
  
  
  METHODS
  Within birth gestation groups, sex ratios were calculated to evaluate any male excess in the CP cohort compared with livebirths, neonatal deaths, neonatal mortality and survival rates, neonatal survivors, and CP rates in survivors. Sex- and gestation-specific trends in neonatal mortality, CP rates, and CP sex ratios were assessed by plotting their annual frequencies and fitting quadratic curves.
  
  
  RESULTS
  Over-representation of males in preterm live births partly explained the male excess in the CP cohort after preterm birth, especially at 28 to 31 weeks. Higher CP rates in male neonatal survivors also contributed to the male excess in CP, particularly at <28 and 37+ weeks. Higher neonatal mortality rates in males at all gestations had little impact on the CP sex ratio. There was no clearly discernible change over time in the CP sex ratio.
  
  
  CONCLUSIONS
  Gestation-specific associations between sex and CP provide insight into causal pathways to CP and suggest sex-specific differences in response to neuroprotective strategies.
authors.affiliation: Developmental Disability & Rehabilitation Research, Murdoch Childrens Research Institute, Melbourne, VIC, Australia.|Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Reid
authors.affiliation: Developmental Disability & Rehabilitation Research, Murdoch Childrens Research Institute, Melbourne, VIC, Australia.|Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Elaine
authors.initials: E
authors.lastname: Meehan
authors.affiliation: South Australian Birth Defects Register, Women's and Children's Hospital, Women's and Children's Health Network, Adelaide, SA, Australia.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Gibson
authors.affiliation: South Australian Birth Defects Register, Women's and Children's Hospital, Women's and Children's Health Network, Adelaide, SA, Australia.
authors.forename: Heather
authors.initials: H
authors.lastname: Scott
authors.affiliation: Cerebral Palsy League, Fortitude Valley, QLD, Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Delacy
mesh_terms: D002547:Cerebral Palsy / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012306:Risk; D012737:Sex Factors; D015996:Survival Rate; D014739:Victoria / Q000453:epidemiology