Developmental delay risk in very and extremely preterm infants at 6 and 12 months corrected age: a prospective cohort study using ASQ-3 in Vietnam

Preterm infants born before 32 weeks of gestation face substantial risks of neurodevelopmental delay. However, longitudinal screening data from low- and middle-income countries using parent-completed tools remain scarce. This study described neonatal morbidity, mortality, growth, and risk of developmental delay at 6 and 12 months corrected age (CA) using the Ages and Stages Questionnaires, Third Edition (ASQ-3) in a Vietnamese cohort of very and extremely preterm infants. A prospective cohort study was conducted at City Children’s Hospital, Ho Chi Minh City. Infants born at less than 32 weeks of gestation admitted within 28 postnatal days from September 2022 to September 2023 were enrolled. Developmental delay risk was screened using the Vietnamese-adapted ASQ-3 at 6 months CA ( n = 51) and 12 months CA ( n = 50). Screen-positive risk was classified as “monitor” (score between − 1 and − 2 SD) or “high risk / refer” (score ≤ − 2 SD in any domain). Anthropometry was assessed at each visit using WHO 2006 z-scores, and Fenton 2013 references were used to define extrauterine growth restriction (EUGR) at discharge. Of 71 enrolled infants (median gestational age 28.4 weeks; median birth weight 1,100 g), in-hospital mortality was 22.5% (16/71). Among 51 infants screened at 6 months CA, 21.6% were classified as high-risk (refer) and 21.6% as monitor for developmental delay; gross motor was the most affected domain (17.6% high-risk). In the 12-month cohort ( n = 50), high risk screen-positive rate increased to 38.0%, the monitor category was 24.0%, and 38.0% screened within normal range; within-child z-score analysis identified gross motor as the domain with the most robust evidence of persistent delay independent of form-specific measurement differences. Extrauterine growth restriction (Fenton 2013) was present in 19.6% at discharge. Anthropometric z-scores (WHO 2006) showed underweight (WAZ < − 2 SD) in 13.7% at 6 months and 12.0% at 12 months CA; microcephaly (HCZ < − 2 SD) increased from 11.8% to 22.0%. Gestational age < 28 weeks and BPD of any grade were each associated in univariate Firth models with approximately fivefold higher odds of high-risk ASQ-3 classification and retained clinically relevant adjusted effect sizes with adequate calibration. In this single- center cohort of infants born before 32 weeks in Vietnam, a substantial proportion screened positive for developmental delay risk on the ASQ-3 across the first year of corrected age. Early, structured follow-up integrating ASQ-3 screening, targeted physiotherapy referral, and close monitoring of head growth and nutritional status should be prioritized in neonatal care pathways in similar resource-limited settings.