The widespread utilization of prenatal ultrasonography and the detection of antenatal hydronephrosis (AH) have raised the importance of postnatal follow-up of these infants. In this study, we aimed to determine the importance of an early diagnosis for the treatment of urinary tract malformations (UTM) as well as the postnatal evaluation of growth and nutrition status and the frequency of urinary tract infection (UTI) in infants with AH. We evaluated 246 infants (183 boys, 63 girls) whose routine antenatal scans showed an anterior-posterior pelvic diameter (APPD) ≥5 mm. Of the 246 patients, 175 (71.1%) were found to be pathological and 71 were evaluated as normal after the follow-up period. The median follow-up periods of normal and abnormal cases were 45.7 and 43.4 months, respectively. All cases with or without UTM were evaluated in terms of UTI, scars on DMSA, growth [Height Z score (HZ), Weight Z score (WZ)] and nutrition [Weight height index (WHI)] status. The annual UTI frequency was higher in cases with UTM (1.32 ± 1.66 episode/year) than in cases without abnormality (0.27 ± 0.67 episode/year) (P < 0.001). The postnatal evaluation of growth and nutritional status in children with UTM (mean WHI, HZ, and WZ scores: 96.82 ± 10.21, 0.03 ± 0.54 and 0.04 ± 0.61, respectively) was found to be significantly worse than in cases without abnormality (102.25 ± 9.84, 0.14 ± 0.64 and 0.24 ± 0.76, respectively), (P < 0.05). In abnormal patients, the mean WHI, HZ, and WZ were significantly improved to 101.63 ± 9.75, 0.26 ± 1.07, and 0.28 ± 0.98, respectively, and HZ or WZ scores were found to be similar when compared to normals. In conclusion, postnatal early management of infants with AH seems to prevent frequent UTIs and nutritional disturbances enabling normal growth.