Analysis of Longitudinal follow-up Data of Physical Growth in Singleton Full-Term Small for Gestational Age Infants

Background: The rate of full-term small for gestational age (SGA) infants is rising worldwide. This study aimed to investigate the catch-up growth pattern of singleton full-term SGA infants in the first of the year. Methods: A single-center retrospective study assessed singleton full-term SGA infants was admitted to the Department of Child Health Care, Chongqing Health Center for Women and Children from August 2015 to December 2018. Weight, length and head circumference were measured at birth, 1 month, 3 months, 6 months and 12 months of age. The Z-score was evaluated. Results: A total 210 SGA infants were included in this study. Boys (n=90) and girls (n=120) showed comparable gestational ages, and birth weights and lengths. Weight, length and head circumference in SGA infants of all age groups were increased, with the fastest growth stage from birth to 3 months. The speeds of weight and head circumference catch-up were higher than that of body length. Birth length was not related to parents' heights in both genders. At 12 months, there were significant associations of body length with father’s height, mother’s height and parents’ heights in boys; in girls, body length showed associations with mother’s height and parents' heights. Conclusions: Full-term SGA infants grow rapidly after birth, with the fastest growth rate in the first three months as examined by weight, length and head circumference. Within 12 months after birth, catch-up was better for weight compared with length. Finally, body length in SGA infants was positively correlated with the parents' heights at 12 months.