Predisposing Factors for Congenital Hearing Loss: A Comprehensive Systematic Review

This systematic review aimed to assess and integrate research on risk factors for congenital hearing loss (CHL), emphasizing genetic, infectious, perinatal, environmental, and sociodemographic influences. The review was prospectively registered with PROSPERO (CRD42022372879) and conducted according to PRISMA 2020 and PRISMA-S guidelines. A comprehensive search was performed across PubMed, Embase, Scopus, and Google Scholar using MeSH terms and free-text keywords related to CHL and its risk factors. Observational studies (cohort, case-control, cross-sectional) involving children with CHL and assessing genetic, infectious, perinatal, or environmental exposures were included. Data extraction was done independently by two reviewers, covering study characteristics, diagnostic methods, and measures of association (odds ratio, relative risk). Risk of bias was evaluated using the Newcastle-Ottawa scale for cohort/case-control studies and the Joanna Briggs Institute checklist for cross-sectional studies. Genetic factors such as GJB2 mutations, a positive family history, and consanguinity were consistently associated with CHL. Infectious etiologies, particularly congenital cytomegalovirus, were prominent across studies, with TORCH infections also commonly implicated. Perinatal risk factors, including neonatal intensive care unit admission, low birth weight, and hyperbilirubinemia, were frequently reported in affected children. Environmental exposures, especially to ototoxic medications, were noted as significant contributors, often acting synergistically with other risk factors like infections or genetic conditions. Sensorineural hearing loss, predominantly bilateral, emerged as the most common type reported. CHL is a multifactorial condition, with genetic and infectious causes being most prevalent. Targeted screening and preventive strategies addressing these risk domains are crucial for early detection and management.