A cross-sectional study on the growth and development of preterm infants during the first year of life in Tibet’s Lhasa Region

Limited data exist on early growth and hematological parameters of preterm infants in high-altitude regions. This study was aimed to examine the growth and neurodevelopmental outcomes and the incidence of anemia and vitamin D deficiency (VDD) during the first year of life in preterm infants residing in Tibet's Lhasa Region. This cross‑sectional study enrolled 228 preterm infants (including 98 small‑for‑gestational‑age [SGA] and 38 very preterm [VP] infants). At each follow‑up visit, 151, 117, 125, and 98 infants completed assessments at corrected ages (CA) of 1, 3, 6, and 12 months, respectively. Anthropometric measurements measured by trained health professionals at CA of 1, 3, 6, and 12 months. Neurodevelopment was assessed using the Infant Neurological Motor Assessment (20-item version, N20) at CA of 1, 3, and 6 months, the Alberta Infant Motor Scale at CA of 3 and 6 months, and the Developmental Screening Test at CA of 12 months. Venous blood samples were collected at CA of 6 and 12 months to determine hemoglobin (Hb, g/L) and serum 25-hydroxyvitamin D (ng/mL) levels. Anemia was defined as Hb < 137 g/L, and VDD was defined as serum 25-hydroxyvitamin D < 20 ng/mL. Preterm SGA infants showed significantly lower Z-scores for height, weight, and head circumference, with higher rates of underweight, stunting, and microcephaly. Similarly, VP infants displayed analogous patterns of compromised physical growth to preterm SGA infants. Furthermore, the SGA group exhibited a higher prevalence of development delay. Both SGA and VP birth were independently identified as significant risk factors for developmental delay. Anemia prevalence was 62.5% (35/56) at 6 months and 48.6% (35/72) at 12 months, while VDD rates decreased from 5% (2/40) to 3.4% (2/59) over the same period. In this high-altitude study, preterm infants as a group exhibited suboptimal growth indicators, a high prevalence of developmental delay, and a significant burden of anemia during their first year. These challenges were most severe in those born SGA or VP. Infants who were neither SGA nor VP showed better growth and neurodevelopmental outcomes. These findings advocate for enhanced surveillance and tailored interventions for all preterm infants, particularly high-risk subgroups, in high-altitude settings.