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Table 1 Comparison of clinical characteristics before matching data between the two groups

From: Relationship between formulaic breast volume and risk of breast cancer based on linear measurements

Covariates Control group Case group Test statistics P value
Age 50.4 (45.0, 54.0) 50.7 (45.0, 57.0) U = 34,589.00 0.668
BMI 23.48 (21.10, 25.26) 23.72 (21.23, 26.04) U = 33,110.50 0.211
Menarche age 14.9 (13.0, 16.0) 14.3 (13.0, 15.0) U = 29,130.00 < 0.001
Age at first pregnancy 23.7 (21.0, 26.0) 24.3 (22.0, 26.0) U = 30,871.50 0.012
Number of pregnancies 3.0 (2.0, 4.0) 3.0 (2.0, 4.0) U = 31,835.50 0.045
Feeding mode    χ2 = 0.350 0.554
 Breastfeeding 316 (92.9%) 196 (94.2%)   
 Non-breastfeeding 24 (7.1%) 12 (5.8%)   
Proliferative benign breast disease    χ2 = 0.984 0.321
 Yes 107 (31.5%) 74 (35.6%)   
 No 233 (68.5%) 134 (64.4%)   
Oral contraceptives    χ2 = 0.009 0.923
 Yes 27 (7.9%) 17 (8.2%)   
 No 313 (92.1%) 191 (91.8%)   
Smoking    χ2 = 1.638 0.201
 Yes 0 1 (0.5%)   
 No 340 (100%) 207 (99.5%)   
Alcohol consumption    χ2 = 4.230 0.121
 No risk 325 (95.6%) 193 (92.8%)   
 Low risk 15 (4.4%) 13 (6.3%)   
 High risk 0 2 (1.0%)   
History of hyperthyroidism    χ2 = 0.292 0.589
 Yes 9 (2.6%) 4 (1.9%)   
 No 331 (97.4%) 204 (98.1%)   
Family history    χ2 = 1.673 0.196
 Yes 8 (2.4%) 9 (4.3%)   
 No 332 (97.6%) 199 (95.7%)