Breastfeeding has been recommended for preterm infants as the optimal diet from nutritional, gastrointestinal, immunological, and developmental perspectives. However, the relevance of differing intakes of fortified mother's own milk (MOM) on the growth of their preterm infants is a challenging question because of the potential risk of extrauterine growth impairment, apart from its essential role in the provision of biological and immunological factors, and the reduction of serious morbidities. We aimed to identify the weight gain pattern in very-preterm-born infants with respect to their proportional intake of fortified MOM. The daily and average weight gain, dietary volume, calories, and proportional intake of fortified MOM were studied in a cohort of 84 very-preterm-born infants during the first 2 weeks post initiation of full enteral feeds. Groups 1, 2, and 3 were comprised of infants with a proportional fortified MOM intake of 85% or more, 35% to 84.9%, and 0 to 34.9%, respectively. Data analysis included regression models and a group-based comparison of the number of infants with weight gain that would be considered minimally acceptable for normal intrauterine growth. The infants' weight gain was not found to be associated with the proportional intake of fortified MOM or other feeding parameters. Overall, the intergroup variability in the proportion of infants with weight gain less than the lower limit of normal fetal growth was insignificant. During the first 2 weeks post initiation of full enteral feeds, the weight gain pattern of the studied very-preterm-born infants was not significantly dependent on the proportional intake of fortified maternal milk.