There was minimal missingness in the data among the final sample of 2,852 participants. We imputed all missing data using the -mi impute chained- command in Stata 17 to create 30 complete, imputed datasets on which multivariate regression analyses were conducted (n=2,852). Missingness at the item and outcome level was low, ranging from 0 – 5%. Logit models indicated that missingness was not associated with observed covariates and outcomes, with one exception.<sup>3</sup> Separate datasets were imputed for each child age group (0-35 months and 36-72 months). Following procedures recommended by White et al. (2010), within each age group, our models allowed for separate imputations by child gender to minimize bias in exploring interactions with child gender.

# **Measures**

# **_Child development outcomes_**

# _Early child development_

Early child development, defined as the essential physical, motor, cognitive, social-emotional and language skills that children develop early in life (Britto, 2017a), was measured for children aged 0-35 months using the short-form Caregiver-Reported Early Development Instrument (CREDI) (McCoy et al., 2018), a 20-item culturally and linguistically neutral questionnaire assessing four domains of development: motor, language, cognition, and social-emotional development. The tool has previously been tested for feasibility and validity and has been used in the Pakistani context (Hentschel et al., 2023; McCoy et al., 2019). Yes/no items were completed by the respondent caregiver about the focal child, asking about developmentally appropriate skills specific to one of six age groups: 0–5, 6–11, 12–17, 18–23, 24– 29, and 30–35 months. De-identified data were scored using the CREDI Scoring App (McCoy et al., 2018). Non-yes/no responses are treated as missing, and observations with fewer than 5 yes/no responses do not receive a score from the app. Scores were standardized by age group, and differences in scores were interpreted in standard deviation units. Internal consistency for each age group was adequate (Cronbach’s alpha coefficient ranging from 0.62 to 0.94).

# _School readiness_

School readiness, defined as children’s development and early learning skills across multiple dimensions of development relevant for school entry, including early academic skills, socialemotional development, and motor development (Snow, 2006; Wolf et al., 2017), was assessed for children aged 36-72 months using adapted items from the Measuring Early Learning Quality and Outcomes (MELQO)-Measure of Development and Early Learning (MODEL) Teacher/Caregiver report (UNESCO, 2017) following expert guidance to ensure socio-cultural relevance. The tool included 25 yes/no questions completed by the respondent caregiver about the child to evaluate school readiness skills across three subdomains: math knowledge and skills, language and literacy knowledge and skills, and socio-emotional development. Twenty of the 25 items are included in the Anchor Items for Measurement of Early Childhood Development (AIM-ECD) tool (World Bank, 2022) which has previously been administered across Pakistan (Ansari et al., 2024). ‘Don't know' responses were treated as missing. Based on the distribution of missingness, minimum

> 3 Missingness in the MELQO-MODEL domain scores for language and literacy knowledge and skills and socioemotional development was associated with lower psychosocial stimulation z-scores. No associations with missingness were found at the item level.

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