title: Sex ratio variations among the offspring of women with diabetes in pregnancy.
abstract: OBJECTIVE
  It has long been hypothesized that natural selection would favour a reproductive strategy biased towards females under adverse circumstances in order to maximize the number of surviving grandchildren. An excess of daughters in women with Type 1 diabetes and a greater likelihood of gestational diabetes in women carrying male fetuses have also been reported. This study aims to compare the sex ratio across categories of maternal glycaemia.
  
  
  METHODS
  Among 288,009 mother-infant pairs delivering at Kaiser Permanente Northern California in 1996-2008, sex ratios were calculated for the following categories: pregravid diabetes, gestational diabetes, mild pregnancy hyperglycaemia (defined as an abnormal screening but normal diagnostic test for gestational diabetes) and normoglycaemia. Odds ratios for delivering a male were estimated with logistic regression; normoglycaemic pregnancies comprised the reference.
  
  
  RESULTS
  Women with pregravid diabetes delivered the fewest males (ratio male/female = 1.01), followed by women with normoglycaemic pregnancies and those with an abnormal screening only (both sex ratios = 1.05); women with gestational diabetes delivered the most males (sex ratio = 1.07). Odds ratio estimates suggested the same pattern, but none attained statistical significance.
  
  
  CONCLUSIONS
  The crude sex ratios in this cohort suggest a possible gradient by category of maternal glycaemia. Women with gestational diabetes, a condition characterized by excessive fuel substrates, appear to deliver more males. Women with pregravid diabetes delivered the fewest males, possibly reflecting the unfavourable state of chronic disease.
authors.affiliation: Division of Research, Kaiser Permanente of Northern California, Oakland, California 94612, USA. samantha.ehrlich@kp.org
authors.forename: S F
authors.initials: SF
authors.lastname: Ehrlich
authors.forename: B
authors.initials: B
authors.lastname: Eskenazi
authors.forename: M M
authors.initials: MM
authors.lastname: Hedderson
authors.forename: A
authors.initials: A
authors.lastname: Ferrara
mesh_terms: D000293:Adolescent; D000328:Adult; D002140:California; D015331:Cohort Studies; D003920:Diabetes Mellitus; D016640:Diabetes, Gestational; D005260:Female; D006801:Humans; D006943:Hyperglycemia; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications; D012189:Retrospective Studies; D012744:Sex Ratio; D055815:Young Adult