Table 1 Participant characteristics.

From: Associations of human milk lactoferrin with measures of physical growth in very preterm infants

Mothers (N)

Total

Tertile 1 0.06–0.13 mg/mL

Tertile 2 0.14–0.22 mg/mL

Tertile 3  >0.22 mg/mL

Pa

64

19

23

22

Age at delivery, years

33.0 (27, 36)

34.0 (29, 39)

31.0 (27, 36)

28.5 (26, 35)

0.16

Lactoferrin, mg/mLb

 Time 1c

0.16 (0.1, 0.2)

0.11 (0.1, 0.1)

0.16 (0.2, 0.2)

0.24 (0.2, 0.3)

<0.01

 Time 2c

0.18 (0.1, 0.3)

0.09 (0.1, 0.1)

0.17 (0.1, 0.2)

0.29 (0.3, 0.4)

<0.01

 Meanc

0.18 (0.1, 0.2)

0.10 (0.1, 0.1)

0.18 (0.2, 0.2)

0.26 (0.2, 0.3)

<0.01

Race, N (%)d

    

<0.01

 Asian

3 (5)

0 (0)

2 (9)

1 (5)

 

 Black

20 (31)

3 (16)

8 (35)

9 (41)

 

 White

27 (42)

15 (79)

6 (26)

6 (27)

 

 Other/unknown

14 (22)

1 (5)

7 (30)

6 (27)

 

Hispanic, N (%)d

13 (21)

0 (0)

5 (24)

8 (36)

0.01

Infants (N)

68

22

23

23

 

Birthweight, g

1068 (858, 1458)

955 (650, 1470)

1060 (865, 1420)

1260 (970, 1460)

0.33

Birthweight, z-score

−0.09 (−0.6, 0.4)

−0.01 (−0.9, 0.4)

−0.25 (−1.1, 1.9)

0.09 (−0.5, 0.4)

0.56

Birth length, cm

36.6 (34, 40)

35.7 (31, 40)

36.4 (34, 40)

37.0 (36, 40)

0.18

Birth length, z-score

−0.07 (−0.5, 0.6)

−0.11 (−0.6, 0.8)

−0.17 (−0.9, 0.6)

0.14 (−0.5, 0.6)

0.46

Birth HC, cm

25.5 (23, 28)

24.9 (22, 28)

25.5 (24, 28)

26.0 (25, 28)

0.32

Birth HC, z-score

−0.34 (−1.0, 0.2)

−0.31 (−1.1, 0.1)

−0.46 (−0.9, 0.1)

−0.29 (−1.1, 0.4)

0.78

GA, weeks

28.5 (27, 30)

27.8 (25, 30)

29.1 (27, 30)

28.6 (27, 31)

0.46

SGA, %d

10 (15)

5 (23)

4 (17)

1 (4)

0.19

Average human milk volume, mL/kg/day

125 (120, 132)

126 (121, 132)

122 (117, 128)

125 (120, 131)

0.50

Average human milk energy, kcal/kg/day

83.4 (78, 91)

84.0 (79, 92)

81.2 (74, 83)

88.5 (80, 92)

0.46

Average human milk protein, g/kg/day

1.55 (1.4, 1.9)

1.37 (1.2, 1.7)

1.57 (1.4, 1.8)

1.58 (1.6, 2.2)

0.04

Anthropometry PMA, weekse

38.3 (36, 40)

39.7 (38, 41)

38.9 (37, 40)

38.0 (36, 40)

0.37

Body composition PMA, weekse

39.4 (37, 40)

39.7 (37, 41)

39.4 (38, 40)

39.1 (38, 40)

0.70

Female, N (%)d

31 (46)

13 (59)

9 (39)

9 (39)

0.30

Twins, N (%)2

12 (18)

7 (32)

2 (9)

3 (13)

0.10

Comorbidities, N (%)d

 NEC

1 (2)

1 (6)

0 (0)

0 (0)

0.35

 Severe IVH or PVL

5 (8)

2 (10)

2 (9)

1 (4)

0.12

 Sepsis/meningitis

3 (5)

1 (5)

2 (9)

0 (0)

0.11

 Steroids for CLD

10 (15)

5 (23)

3 (14)

2 (9)

0.35

 Respiratory support

23 (43)

10 (53)

7 (44)

6 (33)

0.57

  1. All values are median (IQR) or N (%).
  2. Tertile 1 serves as the reference group.
  3. CLD chronic lung disease, GA gestational age, HC head circumference, IVH intraventricular hemorrhage, NEC necrotizing enterocolitis, PMA postmenstrual age, PVL periventricular leukomalacia, SGA small for gestational age.
  4. aANOVA used to test for significant differences in continuous variables across tertiles of human milk lactoferrin.
  5. bNo significant differences in human milk lactoferrin concentrations between timepoints 1 and 2 (P = 0.70).
  6. cKruskal–Wallis used to test for significant differences across tertile groups and Wilcoxon rank sum test used to determine significant differences between tertile groups.
  7. dChi-square tests or Fisher’s exact test used to test for significant differences in categorical variables across tertiles of human milk lactoferrin.
  8. eNo significant differences in PMA at anthropometric assessment and body composition assessment (P = 0.88).
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