Comparison 1. Zinc supplementation versus no zinc (with or without placebo).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Preterm birth	16	7637	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.76, 0.97]
1.1 Low zinc or nutrition	14	7099	Risk Ratio (M‐H, Fixed, 95% CI)	0.87 [0.77, 0.98]
1.2 Normal zinc or nutrition	2	538	Risk Ratio (M‐H, Fixed, 95% CI)	0.64 [0.31, 1.32]
2 Stillbirth or neonatal death	8	5100	Risk Ratio (M‐H, Fixed, 95% CI)	1.12 [0.86, 1.46]
2.1 Low zinc or nutrition: stillbirth or neonatal death	4	1364	Risk Ratio (M‐H, Fixed, 95% CI)	1.57 [0.83, 2.98]
2.2 Low zinc or nutrition: stillbirth or deaths in first 7 days	1	1555	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.71, 1.51]
2.3 Low zinc or nutrition: deaths from 0 to 28 days	1	1498	Risk Ratio (M‐H, Fixed, 95% CI)	1.08 [0.68, 1.71]
2.4 Normal zinc or nutrition: stillbirth or neonatal death	3	683	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.24, 3.65]
3 Birthweight	17	6757	Mean Difference (IV, Fixed, 95% CI)	0.90 [‐22.23, 24.02]
3.1 Low zinc or nutrition	13	5103	Mean Difference (IV, Fixed, 95% CI)	‐9.87 [‐35.70, 15.96]
3.2 Normal zinc or nutrition	4	1654	Mean Difference (IV, Fixed, 95% CI)	44.46 [‐7.49, 96.41]
4 Small‐for‐gestational age	8	4252	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.94, 1.11]
4.1 Low zinc or nutrition	7	4200	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.95, 1.12]
4.2 Normal zinc or nutrition	1	52	Risk Ratio (M‐H, Fixed, 95% CI)	0.24 [0.05, 1.10]
5 Low birthweight	14	5643	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.78, 1.12]
5.1 Low zinc or nutrition	11	4964	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.75, 1.14]
5.2 Normal zinc or nutrition	3	679	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.58, 1.36]
6 Antepartum haemorrhage	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
6.1 Second trimester	1	1206	Risk Ratio (M‐H, Fixed, 95% CI)	1.59 [0.57, 4.45]
6.2 Third trimester	1	1206	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.39, 2.33]
7 Pregnancy hypertension or pre‐eclampsia	7	2975	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.64, 1.08]
8 Prelabour rupture of membranes	2	1691	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.78, 1.11]
9 Post‐term birth	3	1554	Risk Ratio (M‐H, Fixed, 95% CI)	1.09 [0.74, 1.60]
10 Induction of labour	1	52	Risk Ratio (M‐H, Fixed, 95% CI)	0.27 [0.10, 0.73]
11 Any maternal infection	3	1185	Risk Ratio (M‐H, Fixed, 95% CI)	1.06 [0.74, 1.53]
12 Meconium in liquor	2	1385	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.86, 1.56]
13 Caesarean section	6	2164	Risk Ratio (M‐H, Random, 95% CI)	0.95 [0.58, 1.53]
14 Instrumental vaginal birth	1	1206	Risk Ratio (M‐H, Fixed, 95% CI)	1.12 [0.79, 1.59]
15 Retention of placenta	1	179	Risk Ratio (M‐H, Fixed, 95% CI)	6.62 [0.83, 52.71]
16 Postpartum haemorrhage	3	718	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.78, 2.26]
17 Smell dysfunction	1	170	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.55, 1.86]
18 Taste dysfunction	1	170	Risk Ratio (M‐H, Fixed, 95% CI)	0.74 [0.36, 1.50]
19 Fetal heart rate (beats/minute)	1	176	Mean Difference (IV, Fixed, 95% CI)	‐1.20 [‐3.31, 0.91]
20 Fetal heart rate variability (beats/minute)	1	176	Mean Difference (IV, Fixed, 95% CI)	0.60 [0.04, 1.16]
21 Number of fetal accelerations	1	176	Mean Difference (IV, Fixed, 95% CI)	1.9 [0.91, 2.89]
22 Number of fetal movement bouts	1	176	Mean Difference (IV, Fixed, 95% CI)	1.70 [‐2.53, 5.93]
23 Fetal activity level	1	176	Mean Difference (IV, Fixed, 95% CI)	‐0.30 [‐2.66, 2.06]
24 Fetal movement amplitude	1	176	Mean Difference (IV, Fixed, 95% CI)	0.20 [‐0.79, 1.19]
25 Gestational age at birth	7	2857	Mean Difference (IV, Fixed, 95% CI)	0.08 [‐0.07, 0.22]
26 High birthweight	5	2837	Risk Ratio (M‐H, Fixed, 95% CI)	1.00 [0.84, 1.18]
27 Five‐minute Apgar score less than 5	2	1692	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.26, 4.03]
28 Infant head circumference (cm)	7	3991	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.17, 0.11]
29 Blue or floppy (neonatal hypoxia)	1	179	Risk Ratio (M‐H, Fixed, 95% CI)	5.67 [0.70, 46.18]
30 Neonatal sepsis	2	736	Risk Ratio (M‐H, Fixed, 95% CI)	0.17 [0.03, 1.01]
31 Neonatal jaundice	1	179	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.20, 4.56]
32 Respiratory distress syndrome	2	1136	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.40, 1.14]
33 Neonatal intraventricular haemorrhage	1	580	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.14, 6.86]
34 Necrotising enterocolitis	1	580	Risk Ratio (M‐H, Fixed, 95% CI)	1.95 [0.18, 21.34]
35 Neonatal hospital stay	1	580	Mean Difference (IV, Fixed, 95% CI)	‐1.1 [‐2.39, 0.19]
36 Congenital malformation	6	1240	Risk Ratio (M‐H, Fixed, 95% CI)	0.67 [0.33, 1.34]
37 Diarrhoea (episodes/infant over 6 months)	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
37.1 Acute diarrhoea	1	410	Mean Difference (IV, Fixed, 95% CI)	‐0.40 [‐0.79, ‐0.01]
37.2 Persistent diarrhoea	1	410	Mean Difference (IV, Fixed, 95% CI)	0.0 [‐0.13, 0.13]
38 Dysentery (episodes/infant over 6 months)	1	410	Mean Difference (IV, Fixed, 95% CI)	‐0.06 [‐0.12, 0.00]
39 Cough (episodes/infant over 6 months)	1	410	Mean Difference (IV, Fixed, 95% CI)	‐0.20 [‐0.56, 0.16]
40 Acute lower respiratory infection (episodes/infant over 6 months)	1	410	Mean Difference (IV, Fixed, 95% CI)	‐0.10 [‐0.34, 0.14]
41 Impetigo (episodes/infant over 6 months)	1	410	Mean Difference (IV, Fixed, 95% CI)	‐0.30 [‐0.44, ‐0.16]
42 Infant weight‐for‐age (Z‐score)	2		Mean Difference (IV, Random, 95% CI)	Subtotals only
42.1 Z‐score at 6 months	2	304	Mean Difference (IV, Random, 95% CI)	0.20 [‐0.19, 0.59]
42.2 Z‐score at 13 months	1	168	Mean Difference (IV, Random, 95% CI)	‐0.40 [‐0.70, ‐0.10]
43 Infant weight‐for‐height (Z‐score)	1	136	Mean Difference (IV, Fixed, 95% CI)	‐0.05 [‐0.33, 0.23]
44 Infant mid‐upper arm circumference (mm)	3	1844	Mean Difference (IV, Fixed, 95% CI)	0.74 [‐0.17, 1.65]
45 Infant mental development index	1	168	Mean Difference (IV, Fixed, 95% CI)	‐3.30 [‐6.51, ‐0.09]
46 Infant psychomotor development index	1	168	Mean Difference (IV, Fixed, 95% CI)	‐7.0 [‐11.92, ‐2.08]
47 Infant approach	1	168	Mean Difference (IV, Fixed, 95% CI)	0.10 [‐0.38, 0.58]
48 Infant emotional tone	1	168	Mean Difference (IV, Fixed, 95% CI)	‐0.65 [‐1.13, ‐0.17]
49 Infant activity	1	168	Mean Difference (IV, Fixed, 95% CI)	‐0.10 [‐0.43, 0.23]
50 Infant co‐operation	1	168	Mean Difference (IV, Fixed, 95% CI)	‐0.60 [‐1.16, ‐0.04]
51 Infant vocalisation	1	168	Mean Difference (IV, Fixed, 95% CI)	‐0.08 [‐0.54, 0.38]
52 Differential abilities score at 5 years	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
52.1 Non‐verbal ability	1	355	Mean Difference (IV, Fixed, 95% CI)	‐2.40 [‐5.70, 0.90]
52.2 Verbal ability	1	355	Mean Difference (IV, Fixed, 95% CI)	‐0.30 [‐2.56, 1.96]
52.3 General conceptual ability, IQ	1	355	Mean Difference (IV, Fixed, 95% CI)	‐1.10 [‐3.74, 1.54]
53 Visual sequential memory score	1	355	Mean Difference (IV, Fixed, 95% CI)	‐0.80 [‐2.24, 0.64]
54 Auditory sequential memory score	1	355	Mean Difference (IV, Fixed, 95% CI)	0.60 [‐0.65, 1.85]
55 Knox cube score	1	355	Mean Difference (IV, Fixed, 95% CI)	0.10 [‐0.19, 0.39]
56 Gross motor scale score	1	355	Mean Difference (IV, Fixed, 95% CI)	‐2.0 [‐4.79, 0.79]
57 Grooved pegboard score	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
57.1 Dominant hand	1	355	Mean Difference (IV, Fixed, 95% CI)	2.5 [‐1.26, 6.26]
57.2 Non‐dominant hand	1	355	Mean Difference (IV, Fixed, 95% CI)	1.20 [‐2.71, 5.11]
58 Intelligence quotient of infants at 54 months	1	181	Mean Difference (IV, Fixed, 95% CI)	‐0.40 [‐3.33, 2.53]