Optimal Timing of Introduction of Complementary feeding: Protocol for a systematic review and meta-analysis

Abstract Background: The complementary feeding (CF) period accompanies a critical window of vulnerability. During this time, failure to consume adequate energy, protein, vitamins and minerals is a significant concern and can lead to poor growth outcomes, increased susceptibility to infections, allergies, and diseases, and lower developmental potential. It is therefore of utmost importance to determine the most optimal time to start CF. The objective of this review is to assess the impact of early and late of introduction of CF on infant health, nutrition and developmental outcomes.Methods: We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We will search MEDLINE, Embase, CINAHL, CENTRAL, Web of Science, and other databases and key organizational websites using terms related to complementary feeding and infants. We will also search clinicaltrials.gov for ongoing trials. We will include experimental (randomized trials (individually or cluster) and quasi-randomized trials) and observational studies with a concurrent comparison group (cohort (prospective and retrospective), controlled before-after studies and nested case control studies). We will only include studies that enroll infants, living in low, middle- or high-income countries. Outcomes will be assessed for the following two comparisons:1. Early introduction of CF (before 5 months of age) compared to introduction at 5 to 6.9 months of age2. Late introduction of CF (after 7 months) compared to introduction at 5 to 6.9 months of age All the included studies will be screened on Covidence software and analyzed on Review Manager (version 5.4.1) software.Discussion: There are inconsistencies in the existing recommendations for the introduction of CF, as the recommended age for introducing CF ranges between four and six months of age in various international guidelines. It is imperative to evaluate of consequences of both early and late introduction of complementary foods since optimal timing of introduction may have potential beneficial short- and long-term health effects. Systematic review registration: PROSPERO CRD42020218517