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Table 1 Characteristics of the mother-infant dyads by low and high milk cortisol groups

From: Interactions between cortisol and lipids in human milk

  Whole population (n = 100) Low milk cortisol < 3 nmol/L (n = 50) High milk cortisol > 10 nmol/L (n = 50) T-testa / χ2 OR (95% CI)b
Gestational age 40 [36–42] 40 [36–42] 40 [37–42] t = − 1.49 (p = 0.14)  
Infant gender     χ2 = 0.16 (p = 0.67) 1.28 (0.58, 2.81)
Boy 55 (55%) 29 (58%) 26 (52%)   
Girl 45 (45%) 21 (42%) 24 (48%)   
Birth mode     χ2 = 0.08 (p = 0.77) 0.72 (0.23, 2.24)
Vaginal delivery 86 (86%) 44 (88%) 42 (84%)   
Cesarean section 14 (14%) 6 (12%) 8 (16%)   
Mother’s BMI 24 [18–39] 25 [19–39] 24 [18–37] t = 1.74 (p = 0.09)  
Mother’s age 30 [24–44] 31 [24–44] 30 [24–37] t = 2.24 (p = 0.03)  
Education level     χ2 = 1.26 (p = 0.53)c  
Secondary school / vocational education or lower 22 (22%) 12 (24%) 10 (20%)   
Polytechnic 38 (38%) 17 (34%) 21 (42%)   
University/graduate school 33 (33%) 19 (38%) 14 (28%)   
Missing data 7 (7%) 2 (4%) 5 (10%)   
Primiparous     χ2 = 2.69 (p = 0.10) 2.15 (0.95, 4.90)
No 39 (39%) 24 (48%) 15 (30%)   
Yes 61 (61%) 26 (52%) 35 (70%)   
Gestational diabetes     χ2 = 2.82 (p = 0.09) 3.24 (0.96, 11.00)
Yes 15 (15%) 11 (22%) 4 (8%)   
No 85 (85%) 39 (78%) 46 (92%)   
Exclusive breastfeeding     χ2 = 0.9 (p = 0.34) 0.48 (0.15, 1.56)
No 14 (14%) 5 (10%) 9 (18%)   
Yes 84 (84%) 45 (90%) 39 (78%)   
Missing data 2 (2%) 0 (0%) 2 (4%)   
Birth weight 3656 [2705–4940] 3622 [2830–4940] 3690 [2705–4660] t = −0.69 (p = 0.49)  
Milk cortisol concentration (nmol/L) 9 [1–34] 2 [1–3] 15 [10–34] t = − 15.81 (p < 0.001)  
Sampling time as minutes after 08:00 am 319 [30–645] 354 [120–645] 284 [30–555] t = 2.93 (p = 0.004)d  
Infant age at sampling (days) 61 [41–106] 60 [41–85] 62 [46–106] t = − 0.94 (p = 0.35)  
  1. Data is given as mean or number with either range in square brackets or percentage in parentheses
  2. a df = 98
  3. b Crude odds ratio with 95% confidence interval
  4. c χ2 for trend: Linear-to-linear association 0.13, df = 1, p = 0.719
  5. d Data available from 47 dyads in the low cortisol group and 46 dyads in the high cortisol group (df = 91)