Abstract: Objective To explore characteristics and related influencing factors of the catch-up growth of small for gestational age (SGA) infants in North China in two years after birth. Methods Newborn babies born in the Langfang Women and Children’s Health, Hebei province between January 2012 and January 2013 were enrolled in this retrospective cohort study, who were divided into SGA group, appropriate for gestational age (AGA) group and large for gestational age (LGA) group according to birth weight. Data information of infants and mothers were collected. Statistical analysis was performed to explore characteristics and related influencing factors of the catch-up growth of SGA. Results SGA 661 (8.3%), AGA 6,571 (82.5%) and LGA 729 (9.2%) were included in this study. In the SGA group, catch-up growth mainly occurred within 1 year after birth. Correlation analysis showed that the growth rate of body length within 1 year of SGA was negatively correlated with birth weight, birth body length, Apgar score and feeding patterns. It was positively correlated with the placental weight but negatively correlated with fetal/placental weight ratio (F/P). Conclusions Most SGA infants complete catch-up growth at the age of 2, and the catch-up growth mainly occurred within 1 year after birth. Inappropriately heavy placenta and feeding patterns might be related to the catch-up growth of SGA within 1 year after birth.

Key words: Small for gestational age, Catch-up growth, Fetal/placental weight ratio