AIM: To identify various risk factors that may play a significant role in the development of congenital nasolacrimal duct obstruction(CNLDO).METHODS: This observational case-control study included a case group of 122 children less than two years of age with CNLDO who underwent probing and irrigation treatment at the ophthalmology department of Imam Khomeini Hospital in Ahvaz, Iran, from June 2022 to June 2024. A control group of 122 age-matched children without CNLDO was also included for comparison. Data was collected from the children's medical records. RESULTS:The study found a significant correlation between the occurrence of CNLDO and several maternal factors, such as preeclampsia, the use of levothyroxine, hypothyroidism, having more than three pregnancies(gravidity >3), natural pregnancy, and gestational diabetes mellitus. Additionally, in children, factors, such as oxygen therapy, anemia, reflux, jaundice, and a family history of CNLDO in first-degree relatives were associated with CNLDO, and maternal preeclampsia and hypothyroidism were found to significantly increase the risk of developing CNLDO in children.CONCLUSION: Given that CNLDO affects both premature and full-term children, the present findings may potentially facilitate the early identification of children and infants at risk of nasolacrimal duct obstruction, thereby preventing the onset of chronic dacryocystitis.