OBJECTIVE To observe and analyse the hearing outcome in infants with mild-to-moderate sensorineural hearing loss (SNHL) who failed universal newborn hearing screening (UNHS). METHODS This retrospective cohort analysis included infants with mild-to-moderate SNHL and with complete etiological diagnosis and followed up over three years. RESULTS Out of 96 infants with mild-to-moderate SNHL 72 were stable (75%). Only one case was normal (1.04%), ten cases were improved (10.42%), and 13 were deteriorated (13.54%). The pathogenic mutation of GJB2 was the most common cause (50/96, 52.08%), and most of them were homozygous or complex heterozygous mutations of p.V37I (44/50, 88%). There were 11 cases (11.49%) with large vestibular aqueduct syndrome (LVAS) and nine cases (9.38%) with perinatal risk factors. Infants with GJB2 pathogenic mutation and those without certain etiology mostly had unchanged hearing levels, accounting for 84% (42/50) and 84.61% (22/26), respectively. Hearing deterioration in LVAS was associated with seven cases (63.64%). There was no difference in types of outcomes in perinatal risk factor infants, who were more likely to improve than the other groups, but there were three cases (33.3%) deteriorated to profound hearing loss. Comparison of outcomes of different etiologies showed statistically significant difference (Chi-square = 28.673, p = 0.000). CONCLUSIONS Normal and improved hearing in infants with mild-to-moderate SNHL was rare before the age of three, unlike in many previous studies, and appropriate intervention is recommended. However, intervention should be adjusted according to the hearing outcomes because of the possibility of improvement or deterioration. The etiological diagnosis of infants with mild-to-moderate SNHL would be helpful for predicting the outcome and managing intervention.