title: Perceived exertion in physical activity and risk of gestational diabetes mellitus.
abstract: BACKGROUND
  Physical activity has been associated with decreased risk of gestational diabetes mellitus. Expanding on 2 previously published analyses of absolute exertion measures (time spent and energy expended), we assessed the relation between perceived exertion during usual prepregnancy recreational physical activity and gestational diabetes.
  
  
  METHODS
  We analyzed data from a Washington State 1998-2002 case-control study (216 cases, 472 controls) and a 1996-2002 prospective cohort study (897 participants) separately. We used logistic regression models to derive odds ratios (ORs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  Among case-control participants, risk of gestational diabetes was markedly lower for women who reported very strenuous to maximal exertion in usual activity during the year before pregnancy versus those who reported negligible or minimal exertion (adjusted OR = 0.19; CI = 0.15-0.50). There was a direct inverse relation between perceived exertion and risk of gestational diabetes. This relation was also evident among the subset of participants who did not meet physical activity guidelines in the year before pregnancy. Similarly, the OR among cohort participants reporting very strenuous to maximal exertion was 0.57 (0.24-1.37) versus those reporting negligible to moderate exertion.
  
  
  CONCLUSIONS
  These results suggest that risk of gestational diabetes is inversely related to the exertion perceived during recreational physical activity in the year before pregnancy. Perceived exertion may be a valuable addition to behavior and fitness measures in assessing relations between physical activity and pregnancy-related health outcomes.
authors.affiliation: Center for Perinatal Studies, Swedish Medical Center, 747 Broadway, Seattle, WA 98122, USA. clb3@u.washington.edu
authors.forename: Carole B
authors.initials: CB
authors.lastname: Rudra
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.forename: I-Min
authors.initials: IM
authors.lastname: Lee
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Miller
authors.forename: Tanya K
authors.initials: TK
authors.lastname: Sorensen
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D016640:Diabetes, Gestational / Q000453:epidemiology* / Q000503:physiopathology; D015444:Exercise; D005260:Female; D006801:Humans; D005082:Physical Exertion; D011247:Pregnancy; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology