Risk Factors of Congenital Hearing Loss

Congenital hearing loss means hearing loss that is present in an infant at birth. There are case reports of 2 to 4 infants in a thousand are born with sensorineural hearing impairment, making congenital permanent hearing loss the most frequently occurring birth defect (De Leenheer et al. 2011). In general, genetic factors contribute to almost half of the congenital hearing loss cases while the rest are associated with environmental causes and prenatal factors. There are several environmental factors for congenital hearing loss such as fetal ototoxic drug exposure, premature birth, congenital infections, and the list goes on. The definition of hearing impairment is a permanent, unilateral, or bilateral, sensory or conductive loss, averaging 30 dB or more within the frequency range important for speech recognition (Robson 2006). It is doubtless that children’s development in different aspects such as reading, thinking, social skills, language, and academic performance in the future can be greatly influenced by hearing loss. Therefore, awareness regarding risk factors of congenital hearing loss should be created among the parents for them to take note of it. Risk Factors of Congenital Hearing Loss

First and foremost, gestational age and low birth weight can play important roles in causing congenital hearing loss. Premature babies who have a gestational age of fewer than 37 weeks and birth weight less than 1500g have a higher prevalence of hearing loss compared to full-term babies (Kraft et al. 2014). A study has found that the prevalence of hearing loss in a premature baby aged around 31 weeks is around 1.2% up to 7.5% while the prevalence of hearing loss of a premature baby with weight less than 1500 g is around 1.4 % up to 4.8% (Van Dommelen et al. 2015). Moreover, delayed maturation of the auditory system has been postulated as a concern in infants who are hospitalized in Neonatal Intensive Care Unit (NICU) (Univ Frei et al. 2015) because they are more susceptible to necessary medical intervention such as venous access, assisted ventilation and ototoxic drugs (Kraft et al. 2014). Thus, extra precautions must be taken by the parents of a premature baby if there is any suspected developmental delay, especially speech delay which may indicate a hearing loss.