We anticipated that studies would use different developmental scales for evaluating the effect of zinc supplementation on mental and motor development in children. Hence, during the protocol stage, we had planned to combine the data derived from studies using BSID (usually reported as MDI and PDI) into a single composite measure for ease of combination with studies using developmental scales providing a single composite measure of development (for example, Griffiths Mental Developmental Scale). However, after applying the search strategy, eight studies had reported data using BSID and only one study reported data in Griffiths Mental Developmental Scale. It presented an excellent opportunity to report effects on both MDI and PDI separately (given the absolute number and marked preponderance of studies using BSID), so as to delineate the exact developmental domains affected by zinc supplementation further. Hence we decided to include the eight studies reporting data using BSID in the meta‐analysis and to use MDI and PDI, so as to provide the exact benefit of zinc supplementation in terms of BSID units. The study using the Griffiths Mental Developmental Scale (Gardner 2005) has been reported in detail in the text and the Characteristics of included studies table.