Table 2 Summary of subgroup analysis

Duration of skin-to-skin contact

 Neonatal hypoglycaemia

 < 60 min

308 (2)

0.46 (0.08, 2.55)

0.37

70%

0.68

 ≥ 60 min

514 (4)

0.29 (0.08, 1.10)

0.07

52%

 Admission to special care nursery or neonatal intensive care

 < 60 min

191 (1)

5.24 (0.64, 42.66)

0.12

N/A

0.08

 ≥ 60 min

482 (3)

0.74 (0.45, 1.60)

0.34

54%

 Hypothermia

 < 60 min

625 (5)

1.16 (0.82, 1.64)

0.39

22%

0.0005

 ≥ 60 min

1951 (16)

0.34 (0.18, 0.62)

0.0003

83%

 Hyperthermia

 < 60 min

197 (2)

0.80 (0.26, 2.42)

0.69

0%

0.76

 ≥ 60 min

572 (6)

0.66 (0.51, 0.86)

0.002

0%

 Exclusive breastmilk feeding at discharge

 < 60 min

271 (2)

1.25 [0.97, 1.62]

0.08

0%

0.95

 ≥ 60 min

893 (6)

1.27 [0.94, 1.71]

0.12

95%

 Exclusive breastmilk feeding within the period from discharge to 3 months

 < 60 min

199 (1)

1.25 [1.02, 1.54]

0.04

N/A

0.32

 ≥ 60 min

970 (10)

1.44 [1.19, 1.74]

0.0001

63%

 Any breastmilk feeding at discharge

 < 60 min

29 (1)

1.07 [0.89, 1.28]

0.47

N/A

0.07

 ≥ 60 min

156 (2)

1.24 [0.43, 3.55]

0.07

84%

 Blood glucose concentration

 < 60 min

117 (1)

0.52 [0.20, 0.84]

0.001

N/A

0.33

 ≥ 60 min

211 (4)

0.25 [-0.18, 0.69]

0.26

56%

Timing of initiation of skin-to-skin contact

 Neonatal hypoglycaemia

Immediate ≤ 10 min

408 (3)

0.40 (0.11, 1.43)

0.16

42%

0.05

Early > 10 min to 24 h

108 (1)

5.58 (0.27 – 113.50)

0.26

N/A

 > 24 h to discharge

406 (3)

0.15 (0.07, 0.34)

 < 0.0001

0%

 Hypothermia

Immediate ≤ 10 min

1488 (11)

0.67 (0.35, 1.31)

0.25

85%

0.02

Early > 10 min to 24 h

557 (4)

0.63 (0.31, 1.28)

0.20

64%

 > 24 h to discharge

588 (6)

0.25 (0.16, 0.40)

 < 0.0001

0%

 Hyperthermia

Immediate ≤ 10 min

208 (2)

0.71 (0.51, 1.01)

0.05

0%

0.70

Early > 10 min to 24 h

188 (2)

0.56 (0.34, 0.92)

0.02

0%

 > 24 h to discharge

373 (4)

0.71 (0.41, 1.24)

0.23

0%

 Duration of hospital stays (days)

Immediate ≤ 10 min

100 (1)

-1.50 (-3.26, 0.26)

0.09

N/A

0.20

Early > 10 min to 24 h

301 (2)

0.19 (-2.56, 2.94)

0.89

0%

 > 24 h to discharge

2386 (19)

-2.70 [-4.36, -1.03]

0.002

93%

 Exclusive breastmilk feeding at discharge

Immediate ≤ 10 min

553 (4)

1.15 (1.02, 1.30)

0.02

12%

0.62

Early > 10 min to 24 h

449 (4)

1.16 (078, 1.72)

0.48

93%

 > 24 h to discharge

279 (1)

1.25 [1.10, 1.42]

0.0005

N/A

 Exclusive breastmilk feeding within the period from discharge to 3 months

Immediate ≤ 10 min

671 (5)

1.21 [0.98, 1.49]

0.07

52%

0.43

Early > 10 min to 24 h

417 (4)

1.38 [1.21, 1.58]

 < 0.0001

0%

 > 24 h to discharge

823 (3)

1.23 [1.04, 1.45]

0.01

0%

 Exclusive breastmilk feeding within the period from 3 to 6 months

Immediate ≤ 10 min

66 (1)

2.51 [0.11, 59.53]

0.57

N/A

0.62

Early > 10 min to 24 h

26 (1)

1.07 [0.37, 3.11]

0.90

N/A

 > 24 h to discharge

0

-

-

-

 Any breastmilk feeding at discharge

Immediate ≤ 10 min

0

-

-

-

0.77

Early > 10 min to 24 h

29 (1)

1.07 [0.89, 1.28]

0.47

N/A

 > 24 h to discharge

30 (1)

1.23 [0.50, 3.00]

0.66

N/A

 Blood glucose concentration

Immediate ≤ 10 min

267 (3)

0.58 [0.36, 0.81]

 < 0.0001

0%

0.03

Early > 10 min to 24 h

44 (1)

0.00 [-0.40, 0.40]

1.00

N/A

 > 24 h to discharge

117 (2)

0.09 [-0.86, 1.05]

0.85

51%

Babies born preterm versus at term

 Neonatal hypoglycaemia

Preterm

248 (2)

1.41 (0.09, 22.99)

0.81

38%

0.90

Term

191 (1)

1.16 (0.27, 5.06)

0.84

N/A

 Admission to special care nursery or neonatal intensive care

Preterm

208 (2)

0.98 (0.74, 1.30)

0.88

2%

0.12

Term

191 (1)

5.24 (0.64, 42.66)

0.12

N/A

 Hypothermia

Preterm

911 (8)

0.57 (0.29, 1.11)

0.10

64%

0.68

Term

590 (5)

0.43 (0.13, 1.43)

0.17

79%

 Exclusive breastmilk feeding at discharge

Preterm

126 (2)

2.01 [0.62, 6.58]

0.25

88%

0.39

Term

482 (5)

1.19 [1.00, 1.41]

0.05

39%

 Exclusive breastmilk feeding within the period from discharge to 3 months

Preterm

154 (3)

2.42 [1.44, 4.08]

0.0009

0%

0.03

Term

781 (7)

1.36 (1.23, 1.51)

 < 0.0001

0%

 Any breastmilk feeding at discharge

Preterm

69 (2)

1.44 [1.00, 2.06]

0.05

0%

0.15

Term

30 (1)

1.07 [0.89, 1.28]

0.47

N/A

 Any breastmilk feeding within the period from discharge to 3 months

Preterm

38 (1)

4.50 [1.13, 17.85]

0.03

N/A

0.04

Term

80 (1)

7.40 [3.24, 16.88]

 < 0.0001

N/A

 Blood glucose concentration

Preterm

70 (1)

-0.48 [-1.58, 0.62]

0.39

N/A

0.22

Term

94 (2)

0.31 [-0.29, 0.90]

0.32

78%

Vaginal birth versus caesarean birth

 Neonatal hypoglycaemia

Vaginal birth

163 (2)

0.20 (0.06, 0.67)^a

0.009

N/A

0.02

Caesarean section

253 (2)

1.56 (0.42, 5.85)

0.51

0%

 Admission to special care nursery or neonatal intensive care

Vaginal birth

274 (1)

0.42 (0.15, 1.15)

0.09

N/A

0.28

Caesarean section

304 (2)

1.49 (0.18, 12.04)

0.71

71%

 Hypothermia

Vaginal birth

1056 (9)

0.48 (0.19, 1.24)

0.13

86%

0.34

Caesarean section

446 (4)

0.89 (0.38, 2.09)

0.79

81%

 Hyperthermia

Vaginal birth

163 (2)

0.78 (0.41, 1.48)

0.52

0%

0.58

Caesarean section

142 (2)

0.47 (0.23, 0.95)

0.04

0%

 Exclusive breastmilk feeding at discharge

Vaginal birth

415 (3)

1.19 [0.99, 1.43]

0.06

67%

0.90

Caesarean section

305 (3)

1.21 (0.96, 1.54)

0.11

0%

 Exclusive breastmilk feeding within the period from discharge to 3 months

Vaginal birth

1081 (10)

1.35 [1.17, 1.55]

 < 0.0001

58%

0.71

Caesarean section

34 (1)

1.60 (0.66, 3.91)

0.30

N/A

 Blood glucose concentration

Vaginal birth

167 (2)

0.56 [0.31, 0.80]

 < 0.0001

0%

0.02

Caesarean section

44 (1)

0.00 [-0.40, 0.40]

1.00

N/A