Table 1. Basic characteristics of included studies and participants and study quality evaluation scores.
| Author, year | Gestational age (weeks) | Birthweight (g) | E:C samples | Experimental group method | Control group method | Feeding method | Outcome indicators | Grade |
|---|---|---|---|---|---|---|---|---|
| Bin-Nun et al., 2005 (11) | 29.8±2.6 | 1,152±262 | 72:73 | Probiotics mixture 1 | Placebo | HM | (a)(b)(d) | A |
| Lin et al., 2008 (12) | N/A | 1,028.9±246.0 | 217:217 | Probiotics mixture 2 | Placebo | HM | (c)(d) | B |
| Samanta et al., 2009 (13) | 30.12±1.63 | 1,172±143 | 91:95 | Probiotics mixture 1 | Placebo | HM | (c)(d)(e) | B |
| Braga et al., 2011 (14) | 29.5±2.5 | 1,194.7±206.3 | 119:112 | Probiotics mixture 2 | Placebo | HM | (c)(d) | B |
| Sari et al., 2011 (15) | 29.5±2.4 | 1,231±262 | 110:111 | Lactobacillus sporogenes | Placebo | HM | (c)(d)(f) | A |
| Demirel et al., 2013 (16) | 28.0 (range, 17–45) | 1,164±261 | 135:136 | Saccharomyces boulardii | Placebo | HM | (c)(d)(e)(f) | B |
| Fernández-Carrocera et al., 2013 (17) | 31.2 (range, 26–35.4) | 1,090 (range, 580–1,495) | 75:75 | Probiotics mixture 3 | Placebo | HM | (a)(c)(d)(e) | A |
| Oncel et al., 2014 (18) | 28.2±2.4 | 1,071±274 | 200:200 | Lactobacillus reuteri | Placebo | HM | (a)(c)(d)(e)(f) | A |
| Van Niekerk et al., 2015 (19) | 24–34 | 500–1,250 | 54:56 | Lactobacillus rhamnosus GG | Placebo | HM | (a)(d) | A |
| Costeloe et al., 2016 (20) | 28 (26.1–29.1) | 1,039±312 | 650:660 | Bifidobacterium breve | Placebo | HM | (a)(d) | A |
multiple-strain probiotics: 1= Bifidobacteria infantis, Streptococcus thermophilus, and Bifidobacteria bifidus; 2= Bifidobacterium and Lactobacillus; 3= Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus plantarum, Bifidobacteruim infantis, and Streptococcus thermophilus. Outcome indicators: (a) overall NEC incidence, (b) NEC severity score, (c) NEC stage ≥2, (d) mortality, (e) length of stay, (f) feeding intolerance. E:C, experimental: control; N/A, not available; HM, human milk; NEC, neonatal necrotizing enterocolitis.