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Table 1 Baseline characteristics of the participants (n = 88,567)

From: The association between early formula and reduced risk of cow’s milk allergy during the first three year of life: a Japanese cohort study

  Analyzed (n = 65,568) [Missing] Not analyzed (n = 22,999) [Missing] Effect sizea
Males (%) 33,416 (51.0) 0 11,990 (52.1) 0 0.01
Gestational age, weeks (SD) 39.2 (1.6) 0 39.2 (1.7) 0 0.02
Birthweight, g (SD) 3,011 (418) 0 3,021 (439) 0 0.01
Maternal age, years (SD) 31.6 (4.8) 0 30.7 (5.2) 4 0.08
Caesarean section (%) 12,771 (19.5) 135 4,697 (20.5) 43 0.01
Maternal allergic diseases (%) 36,113 (55.3) 245 12,387 (54.3) 183 0.01
Maternal smoking during pregnancy (%) 9,357 (14.4) 618 4,977 (22.0) 393 0.09
Maternal education   480   430 0.09
 Junior high school (%) 2,135 (3.3)   1,422 (6.3)   
 High school (%) 47,166 (72.5)   17,161 (76.0)   
 University/graduate school (%) 15,787 (24.3)   3,986 (17.7)   
Family income   4,251   2,131 0.07
 Low (%) 22,822 (37.2)   9,385 (45.0)   
 Middle (%) 20,996 (34.2)   6,521 (31.2)   
 High (%) 17,499 (28.5)   4,962 (23.8)   
Early eczema (%) 15,596 (24.2) 1,169 5,282 (23.5) 492 0.01
Older siblings (%) 34,737 (53.2) 245 13,175 (57.7) 183 0.04
Formula consumption (%)      
 Very early (0–3 months old) 30,540 (46.6) 0 11,806 (52.0) 315 0.05
 Early (3–6 months old) 26,567 (40.5) 0 11,525 (50.1) 0 0.08
 Late (6–12 months old) 28,331 (43.2) 0 12,259 (53.3) 0 0.09
Prevalence of food allergy (%)      
At 6 months old      
 CMA 150 (0.2) 0 80 (0.3) 0 0.01
At 12 months old      
 CMA 682 (1.0) 0 229 (1.0) 4 0.00
  1. CMA cow's milk allergy, SD standard deviation
  2. aEffect size indicates the strength of difference between groups and are calculated as phi/Cramer's V and r using the chi-square and Student's t-tests for categorical and numerical variables, respectively