Comparison 1. Immediate or Early skin‐to‐skin versus standard contact for healthy infants.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Breastfeeding 1 month to 4 months post birth	14	887	Risk Ratio (M‐H, Random, 95% CI)	1.24 [1.07, 1.43]
2 Duration of breastfeeding in days	7	324	Mean Difference (IV, Random, 95% CI)	42.55 [‐1.69, 86.79]
3 SCRIP score first 6 hours post birth	2	81	Std. Mean Difference (IV, Random, 95% CI)	1.24 [0.76, 1.72]
4 Blood glucose mg/dL at 75‐180 minutes post birth	3	144	Mean Difference (IV, Fixed, 95% CI)	10.49 [8.39, 12.59]
5 Infant axillary temperature 90 minutes to 2.5 hours post birth	6	558	Mean Difference (IV, Random, 95% CI)	0.30 [0.13, 0.47]
6 Exclusive breastfeeding at hospital discharge to 1 month post birth	6	711	Risk Ratio (M‐H, Random, 95% CI)	1.30 [1.12, 1.49]
7 Exclusive breastfeeding 6 weeks to 6 months post birth	7	640	Risk Ratio (M‐H, Random, 95% CI)	1.50 [1.18, 1.90]
8 Breastfeeding status day 28 to 1 month post birth	3	245	Mean Difference (IV, Random, 95% CI)	0.86 [‐0.73, 2.44]
9 Breastfeeding 1 year post birth	2	62	Risk Ratio (M‐H, Fixed, 95% CI)	6.19 [0.82, 46.78]
10 Success of the first breastfeeding (IBFAT score)	4	384	Mean Difference (IV, Random, 95% CI)	2.28 [1.41, 3.15]
11 Successful first breastfeeding (IBFAT score 10‐12 or BAT score 8‐12)	5	575	Risk Ratio (M‐H, Random, 95% CI)	1.32 [1.04, 1.67]
12 Suckled during the first 2 hours post birth	1	88	Risk Ratio (M‐H, Fixed, 95% CI)	1.06 [0.83, 1.35]
13 Mean variation in maternal breast temp. 30‐120 minutes post birth	1	132	Mean Difference (IV, Fixed, 95% CI)	0.60 [0.34, 0.86]
14 Breast engorgement ‐ pain, tension, hardness 3 days post birth	2	131	Std. Mean Difference (IV, Fixed, 95% CI)	‐0.41 [‐0.76, ‐0.06]
15 Heart rate 75 minutes to 2 hours post birth	3	183	Mean Difference (IV, Random, 95% CI)	‐3.05 [‐7.84, 1.75]
16 Respiratory rate 75 minutes ‐ 2 hours post birth	4	215	Mean Difference (IV, Random, 95% CI)	‐3.12 [‐6.61, 0.37]
17 Infant did not exceed parameters for stability	1	31	Risk Ratio (M‐H, Fixed, 95% CI)	10.83 [1.63, 72.02]
18 Transferred to the neonatal intensive care unit	2	305	Risk Ratio (M‐H, Fixed, 95% CI)	0.51 [0.20, 1.26]
19 Infant body weight change (grams) day 14 post birth	2	43	Mean Difference (IV, Fixed, 95% CI)	‐6.00 [‐175.60, 159.61]
20 Infant hospital length of stay in hours	2	42	Mean Difference (IV, Random, 95% CI)	‐95.30 [‐368.50, 177.89]
21 Not crying for > 1 minute during 90 minutes	1	29	Risk Ratio (M‐H, Fixed, 95% CI)	12.86 [1.91, 86.44]
22 Amount of crying in minutes during a 75‐minute observation period	1	44	Mean Difference (IV, Fixed, 95% CI)	‐8.01 [‐8.98, ‐7.04]
23 PCERA Maternal positive affective involvement and responsiveness 12 months post birth	1	61	Mean Difference (IV, Fixed, 95% CI)	1.90 [‐1.14, 4.94]
24 PCERA Dydadic mutuality and reciprocity 12 months post birth	1	61	Mean Difference (IV, Fixed, 95% CI)	1.30 [0.24, 2.36]
25 Mother's most certain preference for same postdelivery care in the future	3	439	Risk Ratio (M‐H, Random, 95% CI)	6.04 [2.05, 17.83]
26 Maternal state anxiety 8 hours to 3 days post birth	3	390	Std. Mean Difference (IV, Random, 95% CI)	‐0.32 [‐0.59, ‐0.04]
27 Maternal parenting confidence at 1 month post birth	1	20	Mean Difference (IV, Fixed, 95% CI)	5.60 [‐6.24, 17.44]
28 Breastfeeding 1 month to 4 months post birth: Sensitivity analysis	13	827	Risk Ratio (M‐H, Random, 95% CI)	1.26 [1.14, 1.39]
29 Duration of breastfeeding in days: Sensitivity analysis	6	264	Mean Difference (IV, Random, 95% CI)	63.73 [37.96, 89.50]
30 Heart rate 75 minutes to 2 hrs post birth: Sensitivity analysis	2	94	Mean Difference (IV, Fixed, 95% CI)	‐5.77 [‐7.43, ‐4.11]
31 Respiratory rate 75 minutes to 2 hours post birth: Sensitivity analysis	3	126	Mean Difference (IV, Fixed, 95% CI)	‐4.76 [‐6.12, ‐3.41]
32 Exclusive bf discharge ‐ Marin 2010 sensitivity analysis	6	592	Risk Ratio (M‐H, Random, 95% CI)	1.30 [1.12, 1.52]
33 NICU admission ‐ Marin 2010 sensitivity analysis	2	167	Risk Ratio (M‐H, Fixed, 95% CI)	0.65 [0.21, 2.02]