Objective:To investigate the characteristics of early motor development in small for gestational age (SGA) infants at high risk of brain injury.Methods:This study retrospectively enrolled a total of 81 SGA infants and appropriate for gestational age (AGA) infants who were at high risk of brain injury and attended outpatient follow-up visits in Xi'an Children's Hospital from February to October 2022. Seventeen SGA infants (SGA group) and 24 AGA infants (AGA group) were assessed for motor development using the Test of Infant Motor Performance (TIMP) at 2-5 weeks of corrected age (CA) and 20 SGA infants (SGA group) and 20 AGA infants (AGA group) were assessed at 14-17 weeks of CA. Independent samples t-test, rank-sum test, and Chi-square test were used to compare the demographic characteristics, high-risk factors of brain injury, and TIMP scores between the two groups. Results:At 2-5 weeks and 14-17 weeks of CA, the birth weights of SGA group were both less than those of AGA group [(1 817.1±440.3) vs. (2 630.0±560.9) g, t=－4.98; (1 752.0±434.4) vs. (2 226.3±699.8) g, t=－2.58; both P<0.05], but there were no significant differences in gestational age at birth or high-risk factors of brain injury between the two groups (all P>0.05). (1) At 2-5 weeks of CA: SGA group had lower total TIMP score [(71.6±13.7) vs. (80.5±11.5) scores, t=－2.26, P=0.029], elicited item score [61.0 scores (41.0-85.0 scores) vs. 69.1 scores (49.0-96.0 scores), Z=－2.15, P=0.037], sitting position score [8.8 scores (3.0-19.0 scores) vs. 11.2 scores (5.0-22.0 scores), Z=－2.07, P=0.038], and prone position score [(9.8±3.1) vs. (12.3±3.1) scores, t=－2.19, P=0.034] when compared with AGA group. (2) At 14-17 weeks of CA: The standing position score of the SGA group was lower than that of the AGA group [6.5 scores (4.0-11.0 scores) vs. 7.7 scores (2.0-11.0 scores), Z=－2.05, P=0.040], but no statistical difference was observed in the total TIMP score or the scores of sitting, supine, prone, turning, and lateral positions between the two groups (all P>0.05). Conclusion:Early motor performance of SGA infants is inferior to AGA infants before five months of age, which is embodied in the poor head control at 2-5 weeks of CA that further affects the stability of standing posture in them at 14-17 weeks of CA.