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Table 1 Basal characteristics and exposure levels in 489 mother-baby pairs

From: Effects of intrauterine exposures to polychlorinated biphenyls, methylmercury, and lead on birth weight in Japanese male and female newborns

  Male newborns (n = 252) Female newborns (n = 237) p valuea
  Mean ± SD or median and the 5–95 percentiles (or number and %) in parenthesis Mean ± SD or median and the 5–95 percentiles (or number and %) in parenthesis
Maternal characteristics
 Maternal age (years) 31.5 ± 4.3 31.3 ± 4.4 0.497
 Body weight before pregnancy (kg) 53.1 ± 7.4 52.6 ± 8.4 0.511
 Body mass index before pregnancy (kg/m2) 21.0 ± 2.4 20.9 ± 3.3 0.906
 Body weight gain during pregnancy (kg) 9.6 ± 3.7 9.8 ± 3.6 0.584
 Fish/seafood intake during pregnancy (g/day) 51.6 (13.1–109.2) 53.6 (12.2–131.4) 0.201
 Smoking habit during pregnancy (smokers, %) 17 (6.7) 20 (8.4) 0.499
 Drinking habit during pregnancy (drinkers, %) 82 (32.5) 73 (30.8) 0.698
 Delivery type (spontaneous, %) 176 (69.8) 178 (75.1) 0.225
Newborn characteristics
 Gestational age (weeks) 39.5 ± 1.3 39.6 ± 1.2 0.516
 Birth weight (g) 3126 ± 353 3036 ± 314 0.003
 Parity (first-born children, %) 133 (52.8) 123 (51.9) 0.857
Biomarkers in cord blood
 Total PCBs (ng/g-lipid)b 49.4 (16.3–118.6) 44.6 (19.6–107.5) 0.170
 PCB-153 (ng/g-lipid)b 10.6 (3.2–27.9) 9.7 (3.9–23.4) 0.243
 Total mercury (ng/g) 10.2 (4.5–23.8) 9.9 (4.0–21.4) 0.669
 Lead (μg/dL) 1.0 (0.6–1.7) 1.0 (0.5–1.7) 0.252
  1. aStudent t test, Mann-Whitney U test, and Fisher exact test were used for significant difference test
  2. bThese data were used following adjusting for the laboratory