**1. Introduction**

Global efforts through the Millennium Development Goals have been very successful in ensuring many more children survive the perinatal period. However, this has not led to sustained thriving of those same children [1] Estimates now indicate that over 250 million

**Citation:** Gladstone, M.; Lancaster, G.; McCray, G.; Cavallera, V.; Alves, C.R.L.; Maliwichi, L.; Rasheed, M.A.; Dua, T.; Janus, M.; Kariger, P. Validation of the Infant and Young Child Development (IYCD) Indicators in Three Countries: Brazil, Malawi and Pakistan. *Int. J. Environ. Res. Public Health* **2021**, *18*, 6117. https://doi.org/10.3390/

Academic Editor: Verónica Schiariti

Received: 9 April 2021 Accepted: 29 May 2021 Published: 6 June 2021

ijerph18116117

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

children in low- and middle-income countries (LMICs) are at risk of not reaching their developmental potential by five years of age [2]. Early child development (ECD), especially the period from birth to 3 years, is a period of rapid brain development when children are most susceptible to environmental influences, making it the most critical period of development during the lifespan [3]. In many world regions, the very first indication that children are not thriving is registered at the time of school entry, which is much too late for early intervention.

Clearly, more needs to be done to ensure that very early development, in the first 1000 days [4], is better supported to ensure that optimal developmental trajectories are attainable in these children. Those first years are particularly sensitive because of the intensity of brain development. In the early years of life, the brain is extremely responsive both to positive influences, such as stimulating environment and adequate nurturing care, as well as to negative influences, such as poor nutrition, recurrent infections, lack of responsive and secure parenting, lack of early educational support and unstable economic situations. Many early intervention programs have focused on these factors, and some have demonstrated that giving children a good early start in life can critically influence brain development [3] and thus potentially optimize children's future economic and social well-being.

One of the obstacles in promoting policies and programs to effectively support children is the lack of validated and reliable measurement tools that could be used to monitor progress for the youngest age groups. While a number of individual and populationlevel assessments, validated for use in diverse contexts, exist for children at preschool [5], school entry [6] and primary grades [7,8], there is only a small pool of global tools available for children under 3 years. These are mainly developed in Western settings and so costly to implement in low resource settings (e.g., Ages and Stages) or need direct assessment [9], which may require substantial training (Bayley III, Griffiths), making them infeasible for monitoring at the population level. A further challenge is cultural adaptation. If a tool has been specifically developed for a particular country context [10,11], then it may not be readily applied across countries without extensive cultural adaptation, for example, to ensure accurate translation or in the use of relevant props. While some new tools have been created concurrently with the work reported here (e.g., Caregiver Reported Early Developmental Index and Survey of Wellbeing of Young Children) [12], none of them have been developed using an extensive database of child assessments gathered from low- and middle-income countries (LMIC) through a rigorous statistical process [13].

To address these challenges, we recently analyzed 14 datasets comprising 21,083 children; data were collected using seven tools in 10 LMIC countries to identify items that may reliably work across contexts and settings [13]. The resulting prototype tool that we created, the Indicators of Infant and Young Child Development (IYCD), was tested for feasibility of implementation across three sites (Brazil, Malawi and Pakistan) on three continents [14]. At the beginning of this study, the prototype tested comprised 121 items. This tool was created as a simple caregiver-reported tool that was created using tablet-based technology for gathering data (Open Data Kit (ODK)), and it included simple audio/visual media to support understanding of the developmental milestones against which children from 0–3 years were tested.

The present paper outlines the main field testing and final selection of cross-culturally neutral items to validate the WHO IYCD tool across the same three countries, to determine the feasibility of these assessments and to finalize its content. In this study we aimed to determine the performance of the final version of the tool by examining the reliability, ages of attainment and developmental trajectories of each of the IYCD items across countries, as well as in rural and urban settings, in order to ensure that all items in the tool performed consistently across multiple sites, contexts and settings. We also conducted cognitive interviews after to explore language meaning and interpretation in more depth.
