Early catch-up growth status and its influencing factors in small for gestational age preterm infants

Abstract

Objective To study the early physical growth pattern, catch-up growth situation, and the influencing factors of early growth in small for gestational age (SGA) preterm infants. Method Our study was a single center, retrospective study. Criteria for infant inclusion were prematurity, SGA (birth weight less than the 10th percentile of related gender and gestational week, according to Fenton curve 2013), born between January 2012 to October 2015, admitted to our neonatal intensive care unit (NICU) within 24 h after birth, hospitalization more than 7 days, and discharged with complete oral feeding. Corrected age (CA) was used to evaluate growth. According to our follow up plan, anthropometric data (weight, length, head circumference) were collected at corrected full term (40±4 weeks), CA (3±1.5) months and CA (6±1.5) months. Catch-up growth was defined as ΔZ greater than 0.67 compared with that at birth, successful catch-up was defined as anthropometric data higher than 10th percentile in target population. The characteristics and influencing factors were compared between infants with and without catch-up growth. Result Eighty-one SGA preterm infants were involved, 45 boys and 36 girls. The average gestational age was (34.6±1.7) weeks, birth weight was (1 617±348) g, birth length was (41.0±3.2) cm and head circumference was (29.7±2.0) cm. At corrected gestational age (40±4) weeks, CA (3±1.5) months and CA (6±1.5) months, follow-up rate was 86.4%, 66.7% and 58.0%; catch-up growth in weight was 32.9%, 55.6% and 66.0%; successful catch-up growth in weight was 52.9%, 64.8% and 66.0%. At CA (40±4) weeks, there were more boys, sooner recover birth weight, and less patent ductus arteriosus (PDA) in catch-up infants (P<0.05). At CA (3±1.5) months, catch-up infants had large gestational age, and they were longer at discharge, shorter hospital stay, less PDA, and greater body weight at CA 40 weeks, the difference was statistically significant (P<0.05). At CA (6±1.5) months, there were difference in hospitalization days, percentile of body weight at CA 40 weeks and percentile of all three anthropometrics at CA (3±1.5) months between catch-up and no catch-up growth infants (P<0.05). Multiple factor analysis showed that percentile of weight at CA 3 months was the independent risk factor of catch-up growth in weight at CA 6 months (P=0.002, OR=1.221, 95%CI 1.076~1.385). For every 5 percentile increase in body weight percentile at CA (3±1.5) months of age, the likelihood of complete body weight catch-up growth at CA (6±1.5) months increased 2.965 times (95%CI 1.480~5.942). Conclusion Both weight and length of SGA preterm infants showed a trend of rapid gain between corrected gestational age (40±4) weeks to CA (3±1.5) months. The factors that influencing the completion of catch-up growth are different at different age. The weight, length, and head circumference percentile at CA about 3 months are good predictors of growth pattern and situation at CA 6 months for the SGA preterm infants. Key words: Infant, premature; Infant, small for gestational age; Catch-up growth; Risk factors