title: Effect of high parity on the occurrence of prediabetes: a cohort study.
abstract: OBJECTIVE
  To assess the effect of parity on the occurrence of prediabetes defined as an abnormal fasting plasma glucose (5.6-6.9 mmol/l), an abnormal 2-hour oral glucose tolerance test (7.7-11.1 mmol/l), or both, before 12 weeks gestation or at least 6 weeks after delivery.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Nested on a community trial Delaying the Development of Diabetes Mellitus type 2 (AMAL study) in Oman.
  
  
  METHODS
  532 women with a total of 3,196 pregnancies.
  
  
  METHODS
  We conducted sets of Cox proportional hazard regression analyses: crude, age-adjusted and full models which adjusted for maternal age, education, family income and year of delivery.
  
  
  METHODS
  Hazard ratio (HR) of the effect of parity on prediabetes.
  
  
  RESULTS
  We enumerated 258 cases of prediabetes over 8,529 person-years of follow up. In the crude model, high parity (> or =5) pregnancies carried a higher risk of prediabetes than low parity (<5) pregnancies (HR = 3.72; 95% CI = 2.80, 4.91), and the prediabetes incidence rate increased in a dose-response fashion over multiple categories of parity. In age-only models, the association attenuated with control of the confounding effect of maternal age (HR = 1.05; 95% CI = 0.76, 1.45). Adjusting for other confounders in the full models yielded similar results to those adjusted for maternal age only.
  
  
  CONCLUSIONS
  The apparent effect of parity on the occurrence of prediabetes is attributable to the confounding effect of maternal age rather than to high parity.
authors.affiliation: Department of Family Medicine and Public Health, Sultan Qaboos University, Oman. ymfarsi@squ.edu.om
authors.forename: Yahya M
authors.initials: YM
authors.lastname: Al-Farsi
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Brooks
authors.forename: Martha M
authors.initials: MM
authors.lastname: Werler
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Cabral
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Al-Shafei
authors.forename: Henk C
authors.initials: HC
authors.lastname: Wallenburg
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009850:Oman / Q000453:epidemiology; D010298:Parity; D011236:Prediabetic State / Q000453:epidemiology*; D011247:Pregnancy; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment