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Table 2 Gender distribution of first live-born offspring, by maternal characteristics and exposure status.

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

   PCB Exposed   PCB Unexposed  
   Male child
N (%)
Female child
N (%)
Male child
N (%)
Female child
N (%)
   750 (49.8) 756 (50.2) 543 (49.9) 546 (50.1)
Maternal Education     
  Grade school only 35 (52.2) 32 (47.8) 30 (45.5) 36 (54.6)
  Some high school 167 (49.1) 173 (50.9) 120 (49.2) 124 (50.8)
  High school graduate or GED 308 (51.3) 292 (48.7) 262 (49.6) 266 (50.4)
  Some college or professional training 163 (45.0) 199 (55.0) 104 (51.2) 99 (48.8)
  College degree or higher 70 (57.4) 52 (42.6) 24 (63.2) 14 (36.8)
Oral contraceptive use in year prior to conception     
  Yes 76 (54.3) 64 (45.7) 14 (53.9) 12 (46.2)
  No 674 (49.3) 692 (50.7) 529 (49.8) 534 (50.2)
Maternal cigarette consumption prior to conception     
  Yes 295 (51.0) 283 (49.0) 188 (49.9) 189 (50.1)
  No 455 (49.0) 473 (51.0) 355 (49.9) 357 (50.1)
Maternal race/Ethnicity     
  White, non-Hispanic 684 (50.0) 684 (50.0) 478 (49.4) 490 (50.6)
  Other 66 (47.8) 72 (52.2) 65 (53.7) 56 (46.3)
Maternal age at conception     
  18 or younger 35 (54.7) 29 (45.3) 147 (57.9) 107 (42.1)
  19-24 420 (47.7) 460 (52.3) 317(46.6) 363 (53.4)
  25-29 189 (52.2) 173 (47.8) 65 (59.6) 44 (40.4)
  30 or older 106 (53.0) 94 (47.0) 14 (30.4) 32 (69.6)
Maternal BMI at age 20     
  15.0 to < 18.5 112 (52.1) 103 (47.9) 75 (53.6) 65 (46.4)
  18.5 to < 22.0 382 (50.7) 372 (49.3) 261 (48.2) 280 (51.8)
  22.0 to < 25.0 135 (44.9) 166 (55.2) 100 (46.7) 114 (53.3)
  25.0 to < 30.0 44 (50.0) 44 (50.0) 39 (59.1) 27 (40.9)
  30.0+ 18 (58.1) 13 (41.9) 7 (46.7) 8 (53.3)