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Table 4 Menstrual cycle covariates by PBB tertiles from two time frames, Michigan Female Health Study, 1997–1998.

From: Menstrual function among women exposed to polybrominated biphenyls: A follow-up prevalence study

Covariates Tertiles of PBB Estimated at Study Interview (No.) P * (df) Tertiles of PBB Measured at Cohort Enrollment (No.) P * (df)
  Low (112) Middle (113) High (112)   Low (111) Middle (120) High (106)  
Continuous Variables
Mean Age (SD), years 37.7 (6.9) 36.8 (6.1) 38.8 (6.9) 0.07 (2) 38.9 (6.4) 37.1 (6.4) 37.3 (7.2) 0.07 (2)
Mean BMI (SD), kg/m2 25.8 (5.4) 26.9 (6.5) 27.0 (6.8) 0.28 (2) 27.5 (6.4) 26.3 (6.4) 25.8 (5.9) 0.12 (2)
Amount of Weekly Exercise
Low No. (%) 14 (12.5) 17 (15.0) 17 (15.2) 0.27 (4) 13 (11.7) 15 (12.5) 20 (18.9) 0.27 (4)
Moderate No. (%) 38 (33.9) 48 (42.5) 51 (45.5)   41 (36.9) 50 (41.7) 46 (43.4)  
High No. (%) 60 (53.6) 48 (42.5) 44 (39.3)   57 (51.4) 55 (45.8) 40 (37.7)  
Past Year History of Weight Loss = 10%
Without No. (%) 95 (84.8) 97 (85.8) 101 (90.2) 0.45 (2) 97 (87.4) 103 (85.8) 93 (87.7) 0.90 (2)
With No. (%) 17 (15.2) 16 (14.2) 11 (9.8)   14 (12.6) 17 (14.2) 13 (12.3)  
  1. * ANOVA F test for continuous variables; Chi square test for categorical variables.