A Follow-up Study on Physical Growth and Motor Development in Small-for-Gestational-Age Infants

Abstract Background： Small for gestational age (SGA) infants are the high-risk population that need to be paid more attention. The objective of this study was to investigate the patterns of physical growth and motor development in small for gestational age infants during the first two years of life. Methods： A total of 158 SGA infants born between January 2018 and December 2022, who were regularly registered at the Child Health Development Center of Peking University Third Hospital, were enrolled. Body weight, length, head circumference, Peabody Developmental Motor Scales, feeding patterns, and catch-up growth status were assessed at approximately 3, 6, 9, 12, 18 and 24 months of age. Corrected age was used for preterm infants. Results： Overall, 87.3% of SGA infants achieved successful catch-up growth within the first two years of life. SGA infants showed an uneven pattern of physical growth, with relatively more pronounced catch-up in head circumference, and a faster early weight gain compared to length gain. The catch-up patterns for different anthropometric indicators and at different months of age differed between preterm and term SGA infants. Preterm SGA infants exhibited more rapid catch-up in weight and length in the early period, whereas term SGA infants demonstrated more prominent long-term catch-up growth in head circumference. Analysis of factors influencing catch-up growth revealed that maternal diabetes during pregnancy affected the occurrence of catch-up growth in SGA infants. Multivariate logistic regression analysis indicated that fortified breast milk feeding at 3 months (aOR=3.890, 95%CI: 1.103~13.721) and 6 months (aOR=10.432, 95%CI：1.812~60.052，P=0.009) was associated with catch-up growth in SGA infants. Gross motor quotient and total developmental quotient exhibited a nonlinear trend of initial decline followed by an increase, with the lowest point occurring around 12 months of age. Conclusion： The physical growth trajectory and motor development of SGA infants have distinct characteristics. Fortified breast milk feeding was associated with catch-up growth. 12 months of age may be a critical time point for motor-development surveillance, especially females and those born to GDM-complicated mothers.The underlying mechanisms require further investigation, and validation through multicenter, large-sample studies is needed.