Background: There is an assumption that fetus with restricted growth with an inappropriate intrauterine environment lies under stress. Although small-for-gestational-age (SGA) infants have higher mortality, difference in the outcome of SGA and appropriate-for-gestational-age (AGA) infants regarding respiratory morbidity is controversial. It seems that respiratory morbidities in SGA neonates is different from neonates with AGA. In this study, we intend to compare the mortality and respiratory morbidity rates between the preterm small for gestational age (SGA) and appropriate for age (AGA) neonates of less than 34 weeks of gestation. Methods: This analytical cross-sectional study was conducted on 498 preterm neonates with gestational age of < 34 weeks, admitted to the Neonatal Intensive Care Unit. These neonates were categorized into two groups of SGA (n=210) and AGA (n=286). The data analysis was performed, using Student’s t-test and Mann-Whitney U test for parametric variables and Chi-square and Fisher’s exact tests for nonparametric data. Results: According to the results of the study, the two groups were significantly different in terms of their birth weight (P<0.001), pregnancy-induced hypertension (P<0.001), and antenatal steroid usage (P=0.011). Furthermore, respiratory distress syndrome (RDS) was found to be more prevalent in the premature AGA neonates than the SGA ones (P=0.011). In addition, surfactant usage was significantly less in the SGA group (P=0.0006). Bronchopulmonary dysplasia (BPD) developed in 14% and 9% of the premature AGA and SGA neonates, respectively (P=0.094). However, there was no significant difference between the two groups regarding the mortality rate, intra-ventricular hemorrhage, and necrotizing enterocolitis. Among the survived neonates, mean length of hospital stay was significantly higher in the premature SGA newborns born within 26-36 weeks of gestation than their AGA counterparts. Conclusion: As the findings of the current study demonstrated, the mortality rate was similar in the SGA and AGA groups; however, the respiratory morbidities such as RDS and BPD were more prevalent in the AGA neonates.
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