This was an analytical cross-sectional study.

The study sample included 292 children selected with the purposive sampling method. Inclusion criteria were: under five years of age, three months post–COVID-19 infection, negative PCR test results, and hospitalization for COVID-19 between July 2021 and December 2022. If a respondent had passed away or their parents declined participation, they were excluded from the study.

The instruments used included a demographic questionnaire and the Prescreening Developmental Questionnaire (PDQ), based on age groups.

Respondent data were retrieved from the medical records of a top referral hospital in Jakarta. Addresses were provided to enumerators for direct data collection at each respondent’s home. This study involved 15 enumerators, who underwent training sessions covering PDQ administration, weight and height measurements. Inter-rater reliability was assessed using Cohen κ, with values ranging from 0.61 to 1. The lowest κ value recorded among the enumerators was 0.783, indicating a high degree of consistency between the researcher and enumerators.

The data were analyzed using SPSS software (version 25.0; IBM Corp). Normality testing was conducted using the Kolmogorov-Smirnov test for numerical data, which yielded P<.05, indicating non-normal distribution. Bivariate analysis of categorical data was performed using the χ² test. Numerical-categorical data were analyzed using the Mann-Whitney test. Multivariate analysis was conducted by multiple logistic regression.

Ethical approval was obtained from the Fakultas Kedokteran Universitas Indonesia (FKUI) - Cipto Mangunkusumo Hospital Ethical Committee (approval number: KET-668/UN2.F1/ETIK/PPM.00.02/2023). Informed consent was obtained from the parents, and all patients’ identities were kept confidential. To protect participant privacy and confidentiality, all personal identifiers were removed during data collection, and the data were fully anonymized before analysis. Access to the raw data was restricted to authorized research personnel only. Participation in the study was entirely voluntary, and no compensation was offered for involvement.

This study found no significant association between age and child development, contrasting with prior findings linking nutritional status to early developmental outcomes. Galasso & Wagstaff [15] reported a positive correlation between nutrition and development in children under 5 years of age [15], while Shrestha et al [16] emphasized the risks of wasting and underweight status [16]. Although early malnutrition is associated with poor cognitive and motor outcomes [17], our null findings may reflect differences in age distribution, sample characteristics, or developmental assessments.

In contrast to Androutsos et al [9] and Xiao et al [18], who found behavioral issues in children aged 6‐7 years during and after lockdowns, we found no link between age or COVID-19 severity and development. This discrepancy could be due to milder illness in our cohort or differing definitions of severity.

While previous literature often shows gender disparities—such as boys being more prone to stunting due to biological and sociocultural factors [5,8]—we found no significant gender effect. This may be attributed to our sample size, local caregiving practices, or statistical adjustments that controlled for confounding variables.

Although comorbidities such as malnutrition and coronary heart disease increase COVID-19 mortality risk in children [19], our study found no association between these comorbidities and growth or development. This could be due to the low prevalence of those comorbidities (ie, malnutrition and coronary heart disease), milder disease, or differences in comorbidity definitions.

Severe malnutrition is widely linked to developmental delays, with some studies reporting delays in more than >60% of affected children. However, our severity variable was not significant, possibly due to inconsistent classification, low disease severity among children, or the influence of statistical controls diminishing its apparent effect.

Respiratory and neurological impacts of COVID-19, as reported by Bögli et al [20], did not emerge as significant in our cohort—possibly due to the predominance of mild presentation.

Coronary heart disease is known to impair motor development due to chronic hypoxia [21], and febrile seizures in children with epilepsy can lead to neurological damage [22]. These conditions, while important, were infrequent in our population.

Finally, while Ludvigsson [1] argued it was too early to determine if children under 3 years of age are more vulnerable to COVID-19, newborns remain at higher risk due to immature immune systems and lack of maternal antibodies [23].

Discharged patient records were no longer accessible via the electronic health records, and medical records officers were only available until 9 PM daily, leading to delayed data retrieval.

Age was significantly correlated with child growth. Significant correlations were also found between comorbidities and length of stay and child development. To improve child health outcomes post–COVID-19, comprehensive discharge planning should be provided to families to ensure continuous stimulation, and community health care services should be optimized to offer follow-up care and monitoring for children posthospitalization.