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Table 1 Characteristics of 4037 pregnancies of female workers in the semiconductor industry

From: The relationship between spontaneous abortion and female workers in the semiconductor industry

  The job held longest  
FAB (N = 2314) PKG (N = 1372) Clerical worker (N = 351) Total (N = 4037) P-value
Age at conception (years)
 Mean ± SD 27.7 ± 3.5 27.8 ± 3.5 29.6 ± 3.1 27.8 ± 3.5 <0.001a
 Post hoc testb b b a   
 ≤29 1747 (75.5) 1023 (74.6) 195 (55.6) 2965 (73.4) <0.001
 30–34 506 (21.9) 304 (22.2) 141 (40.2) 951 (23.6)  
 ≥35 61 (2.6) 45 (3.3) 15 (4.3) 121 (3.0)  
BMI at interview (kg/m2)
 ≤24.9 1911 (82.6) 1104 (80.5) 320 (91.2) 3335 (82.6) <0.001
 ≥25.0 403 (17.4) 268 (19.5) 31 (8.8) 702 (17.4)  
Level of education at interview
 High school 1521 (65.7) 1000 (72.9) 81 (23.1) 2602 (64.5) <0.001
 College/university 793 (34.3) 372 (27.1) 270 (76.9) 1435 (35.5)  
Smoking status at interview
 Non smoker 1843 (79.6) 1114 (81.2) 341 (97.2) 3298 (81.7) <0.001
 Smoker 471 (20.4) 258 (18.8) 10 (2.8) 739 (18.3)  
Pregnancy outcome prior to pregnancy
 Primigravida 1232 (53.2) 744 (54.2) 180 (51.3) 2156 (53.4) 0.358
 Full term delivery 784 (33.9) 426 (31.0) 124 (35.3) 1334 (33.0)  
 Preterm delivery 32 (1.4) 18 (1.3) 7 (2.0) 57 (1.4)  
 Spontaneous abortion 200 (8.6) 137 (10.0) 24 (6.8) 361 (8.9)  
 Induced abortion 52 (2.2) 38 (2.8) 13 (3.7) 103 (2.6)  
 Stillbirth 14 (0.6) 9 (0.7) 3 (0.9) 26 (0.6)  
Duration of employment at conception (years)
 Median (IQR) 7.6 (5.3–10.5) 8.0 (5.6–10.9) 7.3 (4.9–10.5) 7.8 (5.3–10.7) 0.009c
 Post hoc testd a b a   
 ≤4 523 (22.6) 255 (18.6) 94 (26.8) 872 (21.6) 0.004
 5–9 1123 (48.5) 685 (49.9) 154 (43.9) 1962 (48.6)  
 ≥10 668 (28.9) 432 (31.5) 103 (29.3) 1203 (29.8)  
Year of conception
 ≥2009 1466 (63.4) 867 (63.2) 212 (60.4) 2545 (63.0) 0.559
 ≤2008 848 (36.6) 505 (36.8) 139 (39.6) 1492 (37.0)  
Study plant
 A plant 1369 (59.2) 740 (53.9) 274 (78.1) 2383 (59.0) <0.001
 B plant 945 (40.8) 632 (46.1) 77 (21.9) 1654 (41.0)  
Work schedule
 Days only 235 (10.2) 125 (9.1) 299 (85.2) 659 (16.3) <0.001
 Rotating shift 2079 (89.8) 1247 (90.9) 52 (14.8) 3378 (83.7)  
  1. FAB fabrication process worker, PKG package process worker
  2. Smokers included current and former smokers
  3. SD standard deviation, BMI body mass index, IQR interquartile range
  4. aWelch one-way analysis of variance
  5. bGames-Howell test
  6. cKruskal-Wallis test
  7. dPairwise comparisons