Stunting, underweight and thinness in internationally adopted children: prevalence and associated factors in a large cohort study.

Internationally adopted children (IAC) are at high risk of growth impairment due to early-life deprivation, institutional care, and prenatal exposures. Data on determinants of stunting and other forms of malnutrition in this population remain limited. To evaluate the prevalence of stunting, underweight, and thinness, and to identify factors associated with these conditions in a large cohort of internationally adopted children (IAC), we conducted a large cohort study including 1,955 IAC referred to a tertiary pediatric center in Italy between 2015 and 2025. The cohort mainly included children aged 5-9 years (52.2%) and 1-4 years (33.8%), while only a minority were younger than 1 year or older than 14 years. Growth parameters were assessed using WHO standards. Stunting (HAZ < - 2 SD) and thinness (BMIZ < - 2 SD) were assessed in children aged 1 month to 18 years, while underweight (WAZ < - 2 SD) was evaluated in children younger than 10 years. Demographic, clinical, and laboratory variables were analyzed using a population-averaged generalized estimating equations (GEE) model, followed by univariate and multivariable logistic regression analyses for specific growth outcomes. An interaction analysis between low ferritin and abnormal TSH was also performed. A total of 1,955 internationally adopted children (IAC) were included in the analysis. Stunting was observed in 12.2% of children, underweight in 12.7%, and thinness in 5.6%. In the GEE model evaluating overall growth impairment (stunting, underweight and thinness), independent risk factors included anemia, younger age (1-4 years), Asian origin, and fetal alcohol spectrum disorder (FASD), with FASD showing the strongest association (OR 4.77, 95% CI 3.32-6.86; p < 0.001). In outcome specific univariate analyses, independent predictors of stunting included age 1-4 years (OR 3.09), Asian origin (OR 1.48), anemia (OR 2.30), FASD (OR 4.26), and abnormal thyroid-stimulating hormone (TSH) levels (OR 1.83). Anemia was significantly associated with parasitic infections (p = 0.05), supporting a potential contribution of infectious burden to nutritional impairment. Among children with available ferritin and thyroid data, hypoferritinemia was significantly associated with abnormal TSH levels (p = 0.024); however, this association was not confirmed in univariate logistic regression. Conclusions: A high prevalence of stunting persists among IAC at first presentation to our center. Both prenatal factors, particularly FASD, and postnatal conditions contribute to malnutrition. Early comprehensive screening, including nutritional, infectious, and endocrine assessment, is essential to identify at-risk children and guide targeted interventions. What is known- What is new: The IAC are at high risk of growth impairment due to early-life deprivation, institutional care, and prenatal exposures, with stunting frequently reported at arrival. In this large cohort of IAC, stunting affected 12.2% of children and was independently associated with FASD, young age, Asian origin, and anemia, highlighting the combined role of prenatal and postnatal factors and the need for comprehensive early screening.