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Table 1 Characteristics of primipara, by plant

From: Maternal exposure to polychlorinated biphenyls and the secondary sex ratio: an occupational cohort study

   Indiana Plant
(n = 173)
Massachusetts Plant
(n = 1481)
New York Plant
(n = 941)
PCB production years a 1957-1977 1938-1977 1948-1977
Estimated cumulative occupational PCB exposure, to estimated date of conception b    
  Median 4,868 193,320 20,988
  Interquartile range 2,460-8,510 84,672-397,512 8,700-54,120
Duration of employment (years), prior to estimated date of conception c    
  Median 2.0 2.6 2.0
  Interquartile range 1.1-2.7 1.3-4.6 1.1-3.5
Occupationally PCB exposed prior to estimated date of conception (n, %) 86 (49.7%) 1,034 (69.8%) 386 (41.0%)
Reproductive history reported by proxy 2 (1.2%) 190 (12.8%) 82 (8.7%)
Gender of offspring (n, %)    
  Males 85 (49.1%) 724 (48.9%) 484 (51.4%)
  Females 88 (50.9%) 757 (51.1%) 457 (48.6%)
Maternal race/ethnicitiy (n, %)    
  White, non-Hispanic 165 (95.4%) 1,234 (83.3%) 914 (97.1%)
  Non-white or multiracial 8 (4.6%) 247 (16.7%) 27 (2.9%)
Maternal education (n, %)    
  Grade school only 1 (0.6%) 125 (8.6%) 7 (0.8%)
  Some high school 9 (5.2%) 477 (32.7%) 98 (10.5%)
  High school graduate or GED 69 (39.9%) 522 (35.8%) 537(57.3%)
  Some college or professional training 75 (43.4%) 261 (17.9%) 229(24.4%)
  College degree or higher 19 (11%) 74 (5.1%) 67 (7.1%)
Maternal Age (n, %)    
  18 or younger 30 (17.3%) 141 (9.5%) 147 (15.6%)
  19-24 100 (57.8%) 910 (61.4%) 550 (58.5%)
  25-29 29 (16.8%) 286 (19.3%) 156 (16.6%)
  30 or older 14 (8.1%) 144 (9.7%) 88 (9.4%)
  1. IR = interquartile range
  2. a Births occurring prior to the earliest dates of PCB production at each plant were excluded
  3. b Cumulative exposure was estimated using the combined inhalation-dermal job exposure matrix
  4. c Employment refers to time worked while PCBs were in use at the plants.