Table 1.

PICOS criteria for inclusion of studies

Criterion	Description
Participants	Infants born premature (<37 wk’ gestation) or with a birth weight <2500 g
Intervention	Iron supplementation through the enteral route, ie, medicinal iron, infant formula, human milk fortifier
Comparison	Different regimens of enteral iron supplementation, with respect to dose, duration, and timing of initiation of supplementation
Outcomes	1. Iron status during and/or post the intervention period:
	a) Indices reflecting storage iron (ferritin), transport iron (iron, transferrin, TIBC, transferrin saturation, soluble transferrin receptors), and functional iron (MCV, hematocrit, hemoglobin)
	b) Prevalence of iron deficiency, iron deficiency anemia, and iron overload (as defined by study investigators)
	2. Growth-related parameters during and/or post the intervention period, including weight, length, and head circumference
	3. Measures of neurological development during and/or post the intervention period, assessed through standardized neurodevelopmental assessments performed at predefined time points
	4. Incidence of adverse short-term clinical outcomes (including NEC, ROP, CLD, PVL, oxidative stress, and sepsis) as defined by study investigators during and/or post the intervention period
Study design	Any intervention study, including RCTs and nonrandomized trials

Abbreviations: CLD, chronic lung disease; MCV, mean corpuscular volume; NEC, necrotizing enterocolitis; PVL, periventricular leukomalacia; RCT, randomized controlled trial; ROP, retinopathy of prematurity; TIBC, total iron-binding capacity.