Differences in growth patterns and catch-up growth of small for gestational age preterm infants fed on fortified mother's own milk v. preterm formula

Small for gestational age (SGA) is typically defined as birth weight < 10th percentile for age. Limited data are available regarding the growth of SGA preterm infants in relation to feeding type. We aimed to study SGA preterm infants fed fortified mother's own milk (MOM) or preterm formula (PF) on growth patterns and catch-up growth at discharge and 2-year corrected age (CA). Our retrospective cohort study included data from medical records and follow-up questionnaires about SGA preterm infants born at < 37 weeks fed on MOM (n 40) and PF (n 40). Weight, length/height and head circumference (HC) were collected at birth, discharge and at 2-year CA, and Delta z-scores were calculated. The MOM group had significantly larger negative change in weight and length z-scores between birth and discharge, and smaller positive change in HC z-score (-0 center dot 47 (sd 0 center dot 41) v. -0 center dot 25 (sd 0 center dot 36), P = 0 center dot 01; -0 center dot 63 (sd 0 center dot 75) v. -0 center dot 27 (sd 0 center dot 75), P = 0 center dot 03; 0 center dot 13 (sd 0 center dot 67) v. 0 center dot 41 (sd 0 center dot 55), P = 0 center dot 04, respectively). Almost half of the MOM-fed infants experienced poor length growth by discharge compared with 22 % of PF-fed infants (P = 0 center dot 03). By 2-year CA, both groups had similar positive change in weight and HC z-scores, but MOM-fed infants had a slower increase in height z-score (0 center dot 64 (sd 1 center dot 30) v. 1 center dot 33 (sd 1 center dot 33), P = 0 center dot 02), and only 40 % had achieved catch-up height compared with 68 % of the PF group (P = 0 center dot 02). Our study indicates that fortified MOM-fed SGA preterm infants may need extra nutritional support in the first 2 years of life to achieve height growth potential.