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Table 1 Distribution of blood manganese concentration and birth weight by general characteristics of the study subjects

From: Maternal blood manganese level and birth weight: a MOCEH birth cohort study

  Maternal blood Mn (μg/L) Birth weight (g)
  N (%) Mean ± SD p-value Mean ± SD p-value
Total 331 (100) 22.5 ± 7.2 - 3,303.9 ± 367.6 -
Infant sex       
 Male 166 (50.2) 22.7 ± 7.5 0.521 3,359.2 ± 388.7 0.004
 Female 160 (48.3) 22.2 ± 6.5 3,242.6 ± 331.6
 Missing 5 (1.5) 25.4 ± 15.1 - 4060.0 -
Gestational age (days)       
 <268 79 (23.9) 20.9 ± 8.1 0.067 3,252.4 ± 363.6 <.001
 268-272 73 (22.0) 22.9 ± 6.7 3,169.5 ± 333.6
 273-277 54 (16.3) 22.8 ± 7.1 3,292.2 ± 346.0
 278-282 67 (20.2) 23.1 ± 6.7 3,447.4 ± 385.8
 ≥283 58 (17.5) 23.2 ± 7.0 3,389.8 ± 346.2
Maternal age (years)       
 <28 104 (31.4) 22.5 ± 7.6 0.781 3,312.6 ± 343.7 0.996
 28-29 90 (27.2) 21.1 ± 6.8 3,282.2 ± 395.9
 30-32 82 (24.8) 22.8 ± 6.7 3,326.3 ± 372.3
 ≥33 54 (16.3) 22.6 ± 7.8 3,296.4 ± 364.0
 Missing 1 (0.3) 29.8 - 2,920.0 -
Maternal education       
 High school or less 85 (25.7) 22.7 ± 7.3 0.794 3,337.5 ± 398.7 0.400
 University or above 230 (69.5) 22.5 ± 7.1 3,301.1 ± 359.7
 Missing 16 (4.8) 21.8 ± 8.2 - 3,166.9 ± 284.6 -
Maternal income (million KRW per month)       
 <200 81 (24.5) 22.8 ± 6.4 0.961 3,280.6 ± 391.4 0.276
 200-299 117 (35.3) 21.8 ± 7.3 3,295.7 ± 375.6
 ≥300 118 (35.6) 22.9 ± 7.2 3,336.5 ± 349.7
 Missing 15 (4.5) 22.3 ± 9.7 - 3,233.6 ± 315.7 -
Maternal parity       
 No 134 (40.5) 22.3 ± 6.4 0.363 3,281.9 ± 358.9 0.821
 ≥1 151 (45.6) 22.4 ± 7.9 3,334.4 ± 370.5
 Missing 46 (13.9) 23.5 ± 6.9 3,265.0 ± 382.0
Maternal term weight (kg)       
 <61 54 (16.3) 24.4 ± 8.5 0.736 3,182.4 ± 333.6 0.003
 61-64 56 (16.9) 21.6 ± 7.0 3,244.6 ± 283.0
 65-68 36 (10.9) 21.6 ± 6.5 3,251.4 ± 383.9
 69-75 50 (15.1) 21.5 ± 4.5 3,368.4 ± 358.0
 ≥76 43 (13.0) 21.7 ± 7.8 3,519.3 ± 426.7
 Missing 92 (27.8) 23.2 ± 7.4 3,295.6 ± 361.2
Maternal blood Mn (μg/L)*       
 <16.9 65 (19.6) - - 3,362.2 ± 386.6 0.167
 16.9 – <20.0 66 (19.9) - - 3,225.3 ± 378.5
 20.0 – <22.9 68 (20.5) - - 3,355.5 ± 345.3
 22.9 – <26.9 66 (19.9) - - 3,270.2 ± 347.9
 >26.9 66 (19.9) - - 3,308.6 ± 371.5
Birth weight (quintile, g)       
 <3000 59 (18.2) 22.7 ± 8.6 0.608 - -
 3000-3199 65 (20.0) 21.5 ± 6.1 - -
 3200-3399 66 (20.3) 21.8 ± 6.0 - -
 3400-3599 64 (19.7) 22.8 ± 7.1 - -
 ≥3600 71 (21.9) 23.2 ± 7.4 - -
  1. Tested by ANOVA (tested for linear trend in case of ordinal variables) or t-test.
  2. 106 KRW = 1050 USD as of Jan 2008.
  3. *The 8 μg/L unit categories of blood Mn.
  4. (N = 331).