Objective To analyze linear growth model of symmetrical and asymmetrical full-term small for gestational age (SGA) infants aged 0 − 1, so as to provide evidence for their early growth monitoring.

Methods A prospective cohort study was used to recruit healthy full-term SGA infants who were born in the obstetrics department of affiliated hospital of Weifang medical university between Jan 1^st, 2020, and Jan 1^st, 2022 as study subjects. Symmetrical and asymmetrical SGA infants were categorized based on their ponderal index. The linear growth model was described through various growth indicators, including growth velocity, changes in length growth, catch-up growth, decelerated growth, and growth retardation. Differences between groups were compared.

Results A total of 135 full-term SGA infants were recruited, including 38 symmetrical SGA and 97 asymmetrical SGA cases. The comparative analysis of the two groups revealed that asymmetrical SGA showed a superior growth level compared to symmetrical SGA in the aspects of a higher Z-score for body length and age-specific body length. Then, symmetrical SGA demonstrated a faster growth rate. The differences were statistically significant (all P < 0.05). During early life stage, symmetrical SGA showed a notable increase in catch-up growth (P < 0.05), and approaching similar growth levels of asymmetrical SGA by age 1 (P > 0.05). Additionally, asymmetrical SGA individuals exhibited a larger proportion of decelerating growth compared to symmetrical SGA individuals, along with a larger proportion of overweight or obesity, reaching 15.46%. The differences were statistically significant (all P < 0.05).

Conclusion Symmetrical SGA infants exhibit a more optimal early linear growth pattern, while asymmetrical SGA infants are at a higher risk for growth imbalances such as decelerated growth, growth retardation, and overweight or obesity, which should be paid much attention by healthcare providers.