title: The relation between small size for gestational age and the sex ratio of children with birth defects.
abstract: BACKGROUND
  Infants with birth defects are more likely to be born small for gestational age (SGA) than are other infants. This study describes a relation noted between the percentage SGA and the percentage male among children with various defect types. The data source was case records collected by the Metropolitan Atlanta Congenital Defects Program, a population-based, active surveillance system, during 1968 through 1998.
  
  
  METHODS
  The study calculated the correlation between the percentage male and the percentage SGA for isolated cases of 44 different defect types for male-dominant and female-dominant defects separately.
  
  
  RESULTS
  The correlation coefficient was -0.47 (P < 0.01) for male-dominant defects and 0.20 (P > 0.05) for female-dominant defects. Male-dominant defects were more likely to show less than 15% SGA and more likely to show the strongest risk differences by sex.
  
  
  CONCLUSIONS
  These results are consistent with genetic causation of strongly skewed sex ratios, at least among male-dominant defects. Review of the literature suggests that defects with sex ratios closer to 1 are likely to have lower recurrence risks and therefore are less likely to be inherited than are other defects with skewed sex ratios. Sex ratios closer to 1 and a high percentage SGA may be markers of acquired or environmental birth defects.
authors.affiliation: National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA. LBP4@cdc.gov
authors.forename: L J
authors.initials: LJ
authors.lastname: Paulozzi
mesh_terms: D000818:Animals; D002487:Centers for Disease Control and Prevention, U.S.; D000013:Congenital Abnormalities / Q000145:classification / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D005845:Georgia / Q000453:epidemiology; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D012307:Risk Factors; D012727:Sex Characteristics; D012744:Sex Ratio; D014481:United States