Abstract
Background: Birth weight is a crucial indicator of infant health. In Iran, child growth monitoring for children under six years old is integrated into the healthcare system. However, existing growth charts have limitations in accurately representing preterm infants. Objectives: This study was conducted to determine the frequency of postnatal growth retardation and its causes in preterm infants from hospitalization to six months after birth. Methods: After informing parents, we recruited 255 preterm singleton infants born at the Afzalipour Medical Education and Health Center in Kerman, Iran, over one year. The Fenton growth chart was used to compare the anthropometric characteristics of the infants at birth, and at ages 7, 14, and 28 days, and then monthly up to 6 months. A special questionnaire also recorded the type of feeding, length of hospital stay, use of mechanical ventilation and oxygen, duration of total parenteral nutrition (TPN), and associated causes and complications. Results: The mean Z-score weights at birth, discharge, one month, three months, and six months were -0.34, -1.19, -0.85, -0.94, and -1.79, respectively. The mean Z-score heights at birth, discharge, one month, three months, and six months were 0.74, 0.20, -0.07, -0.79, and -2.5, respectively. Additionally, the mean Z-scores for head circumference at birth, discharge, one month, and three months were 0.41, -0.19, -0.53, and -1.17, respectively. Deviation from the Fenton preterm growth chart was detected in 109 infants (42.7%) at the time of discharge, 79 infants (31%) at one month, 82 infants (32.2%) at three months, and 134 infants (52.5%) at six months of age. Conclusions: The weight at discharge and the length of NPO [due to surgical problems, feeding intolerance, necrotizing enterocolitis (NEC), etc.] were significantly inversely related. Preterm infants grow more slowly in hospitals, so their longitudinal growth data should be interpreted carefully. The incidence of postnatal growth failure can be reduced by improving NICU quality, optimizing nutrition, and increasing enteral feeding rates.