thresholds to receive domain scores were set: 4/6 items with yes/no responses for math, 8/10 for language, and 6/9 for socio-emotional development. Overall scores were computed only if all domain scores were present. Internal consistency across the three subdomains was adequate (Cronbach’s alpha coefficients of 0.79 (math), 0.94 (language), and 0.81(socio-emotional development).

# **_Risk Factor_**

# _Parental distress_

A survey-specific measure was used to assess participants’ level of distress in the previous 15 days. This included five yes/no questions asking if the participant found it difficult to be affectionate to their child, had been more irritated or angry than usual, found it difficult to sleep, was nervous or anxious, or had been unable to control their worry. Scores ranged from 0 – 5, with 5 indicating the highest level of distress. ‘Don't know' responses were treated as missing. Based on the distribution of missingness, the minimum threshold to receive a score was 3/5 items with yes/no responses. Internal consistency was adequate (Cronbach’s alpha coefficient of 0.87).

# **_Protective factors_**

# _Psychosocial stimulation_

Psychosocial stimulation in the home environment was assessed using the Early Learning Indicator Tool (Hentschel et al., _in preparation_ ). The tool includes 14 yes/no questions regarding the availability of playthings in the home and the amount of caregiver-provided engaging interactions in the last 24 hours. The tool was previously developed and used in Pakistan, and there is evidence supporting its validity in this context (Hentschel et al., 2023; Hentschel et al., _in preparation_ ). Scores range from 0 -14, with 14 indicating the highest level of psychosocial stimulation. Internal consistency was adequate (Cronbach’s alpha coefficient of 0.85).

# _Early childhood education (ECE) enrollment_

Early childhood education (ECE) enrollment was assessed for focal children aged 36-72 months by asking respondents an open-ended item regarding where the child attends school. Responses included the pre-primary service provided in public schools (“ _Katchi_ ”), pre-primary, ECE, play group, and preparatory class.

# **_Socio-demographics_**

The moderating variable **_,_** child gender, was recorded based on the participant’s report of whether the focal child was male or female. Additional socio-demographic variables served as covariates. Maternal and paternal education levels were grouped into two categories: completed less than a primary school education and completed primary school or higher. Maternal and paternal educational attainment levels were collected for all children. Rural residence was recorded based on the participant’s report of whether they lived in an urban or rural area. To assess household size, participants were asked the question “How many people are there in your household?” and answers were recorded as a count of the total number of household members; individual-level data on household members were not collected. Participants also reported their province of residence, the respondent’s gender, the child’s age, and the household’s average monthly expenditure on the mobile phone. Monthly expenditure on a mobile phone was used as a proxy measure for income 7