title: Distortions of sex ratios at birth in the United States; evidence for prenatal gender selection.
abstract: OBJECTIVE
  The normal male to female livebirth sex ratio ranges from 1.03 to 1.07. Higher ratios in China, India and Korea reflect prenatal sex selection. We reviewed sex ratios for US births to investigate potential prenatal sex selection.
  
  
  METHODS
  We reviewed all US livebirths from 1975 to 2002 using National Center for Health Statistics birth certificates in 4-year intervals. We compared the sex ratios of Blacks, Chinese, Filipinos, Asian Indians and Koreans relative to Whites. We also compared the sex ratios by birth order for first, second and third and more births (third+) from 1991 to 2002.
  
  
  RESULTS
  The male to female sex ratio from 1975 to 2002 was 1.053 for Whites, 1.030 (p < 0.01) for Blacks, 1.074 (p < 0.01) for Chinese and 1.073 (p < 0.01) for Filipinos. From 1991 to 2002, the sex ratio increased from 1.071 to 1.086 for Chinese, 1.060 to 1.074 for Filipinos, 1.043 to 1.087 for Asian Indians and 1.069 to 1.088 for Koreans. The highest sex ratios were seen for third+ births to Asian Indians (1.126), Chinese (1.111) and Koreans (1.109).
  
  
  CONCLUSIONS
  The male to female livebirth sex ratio in the United States exceeded expected biological variation for third+ births to Chinese, Asian Indians and Koreans strongly suggesting prenatal sex selection.
authors: Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, CT 06030, USA. jegan@uchc.edu
authors: James F X
authors: JF
authors: Egan
authors: Winston A
authors: WA
authors: Campbell
authors: Audrey
authors: A
authors: Chapman
authors: Alireza A
authors: AA
authors: Shamshirsaz
authors: Padmalatha
authors: P
authors: Gurram
authors: Peter A
authors: PA
authors: Benn
mesh_terms: D015982:Bias; D001722:Birth Order; D005006:Ethnicity / Q000706:statistics & numerical data; D005191:Family Characteristics / Q000208:ethnology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D036801:Parturition / Q000502:physiology; D011153:Population; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000706:statistics & numerical data; D012042:Registries; D012189:Retrospective Studies; D012743:Sex Preselection / Q000706:statistics & numerical data*; D012744:Sex Ratio; D014481:United States / Q000453:epidemiology