early recognition and intervention is very effective in improvement of hearing rehabilitation programs and gaining successful results . nevertheless , most children with hearing impairment will be identified lately due to lack of relevant symptoms and signs , and lack of physicians knowledge . current standards emphasize early recognition of congenital hearing loss especially before age 3 months . considering this issue , programs for early detection of hearing loss among newborns are established in different parts of the world . this study was conducted to find the prevalence of hearing impairment in term newborns in yazd . this was a descriptive - analytic study which was conducted in yazd , a central province in iran , from march 2010 until september 2011 . all full - term newborns ( n = 7250 ) except for those who were admitted to neonatal intensive care unit ( nicu ) who were born in governmental and private hospitals in yazd city entered the study ( 2 governmental and 4 private hospitals ) . a questionnaire about demographic data ( gender , parents ' educational status , mother 's job , consanguinity , and medical history of newborns and their parents , history of congenital or inherited hearing loss , and type of delivery ) was filled for each subject . then oae test was performed in all newborns ( device : accuscreen , madsen , denmark ) during the first 24 hours after birth . oae is a simple , non - invasive , and objective test which includes a series of transient clicks with wide - frequency range . some studies investigated the accuracy of oae for screening ; the sensitivity , specificity , positive predictive and negative predictive values of oae in one of these studies were 77.9% ( 71.3 - 83.4% ) , 80.6% ( 68.8 - 88.9% ) , 92.1% ( 86.6 - 95.6% ) , 55.7% ( 45.2 - 65.6% ) respectively ( . the tests were performed by 5 audiologists who were similarly trained for this screening study . those who failed to respond at the second step too , underwent complementary electrophysiologic tests ( auditory brain stem responses ) . the study was approved by the ethics committee of shahid sadoughi university of medical sciences , yazd . this study was conducted on 7250 full - term newborns consisting of 3345 ( 46.1% ) females and 3905 ( 53.9% ) males . 55.2% of newborns were born by cesarian section and 44.8% by normal vaginal delivery . from 7250 newborns ( 14500 ears ) , in the first step 598 ( 8.2% ) and 682 ( 9.4% ) ears ( right and left , respectively ) failed . in the second step 51 ( 0.7% ) and 58 ( 0.8% ) ears ( right and left , respectively ) failed . table 1 shows the comparison of the frequency of results according to different variables . characteristics of the research subjects and result of otoacoustic emissions oae : otoacoustic emissions c / s : cesarian section , nvd : normal vaginal delivery in the next step abr was employed to confirm the hearing impairment . according to the results of this test , 1 , 8 , 13 , and 32 right ears suffered from mild , moderate , severe and profound hearing loss , respectively . for the left ear considering both ears , 30 newborns ( 0.42% ) suffered from bilateral profound sensorineural hearing loss ( snhl ) , other 10 newborns ( 0.13% ) and 6 newborns ( 0.08% ) suffered from bilateral severe and moderate snhl , respectively . all newborns with severe or profound hearing loss were referred for cochlear implant and hearing aid was prescribed for newborns with moderately severe hearing loss . the prevalence of newborn and infant hearing loss was different in various studies from 1 to 6 in 1000 live births . kennedy and mccann observed hearing impair - ment in 133 per 100.000 persons , most of which were congenital . langagne et al estimated it to occur in 1/1000 infants in medium to profound form . early diagnosis of hearing loss and proper intervention may cause a considerable change in the quality of life of hard - hearing or deaf children . the aim of ehdi ( early hearing detection and intervention ) , a program from the american speech - language - hearing association ( asha ) is to maximize children 's competition power and educational development . without enough opportunity for language learning , the hard - hearing or deaf child will delay in lingual , cognitive , and socio - emotional skills compared to his / her contemporaries . therefore , newborn 's hearing should be evaluated by proper methods in order to find congenital hearing loss early after birth . mankowitz and larson in a study on 646 children with hearing loss , found that the lower child 's age at diagnosis of hearing impairment the better child 's lingual skills . yoshinaga - itano et al found that if deaf or hard - hearing children who are normal regarding cognitive skills , are diagnosed before 6 months old , after appropriate therapeutic intervention , their lingual skills can reach normal range , and their cognitive skills will be appropriate for their lingual skills . in infants hearing screening program and intervention of joint committee of infant hearing ( jcih ) , the best age for diagnosis of hearing impairment and various studies have shown that hard - hearing and deaf children with normal cognitive skills diagnosed before 6 months old with early and proper intervention can gain near normal lingual skills , but these skills were much lower in other children . hearing - impaired children diagnosed before 6 months old and received in - time therapeutic intervention ( e.g. sound amplification devices , and family - centered rehabilitation programs ) , will have better function in oral language , receptive vocabulary , expressive vocabulary and communication behavior for speech recognition and number of vowels and consonants . in this study we assessed newborns ' hearing by oaes and abr . this coverage was higher than that found in the study of amirozi et al which was 98% and the study of abdullah et al which was 89.2% . the prevalence of hearing loss in this study was 6.5 in 1000 newborns , which is more than that in most of the previous studies . this measure was 0.9/1000 in amirozi et al , 4.2/1000 in abdullah et al , 1.5/1000 in parving , and 11.8/1000 in watkin et al . this shows a high prevalence of congenital hearing loss among the newborns of our population . the factors which significantly affected the prevalence of hearing loss included : consanguinity , mothers employment , route of delivery , history of hearing loss in the family and history of mother 's seizure . so newborns of mothers with consanguinity , employment and cesarean section showed significantly higher hearing loss than other newborns , and those newborns with congenital malformation , and low birth weight showed higher prevalence of hearing loss . taghdiri et al found hyperbillirubinemia , asphyxia and low birth weight as the most common risk factors for hearing loss studying newborns admitted to icu . we did not assess the newborns who were admitted to nicu , so some risk factors such as hyperbillirubinemia , and asphyxia could not be evaluated . this study showed a high frequency of congenital hearing loss in yazd population in comparison to other studies even in other parts of iran , so necessity of hearing screening for infants in this area is empasized .
objectivepermanent congenital hearing loss , a common congenital anomaly , may affect speech and language acquisition , academic achievement and social development . 
 current standards emphasize early recognition of congenital hearing loss . 
 this study was conducted to find the prevalence of hearing impairment in term newborns in yazd , iran.methodsthis was a descriptive - analytic study conducted in yazd on 7250 term newborns . 
 otoacoustic emissions ( oaes ) test was performed in all newborns during the first 24 hours after birth . 
 those who failed to respond at the first step were retested 15 days later . 
 those who failed to respond at the second step too , were tested by acoustic brainstem responses ( abr ) test . 
 chi square test was used for data analysis.findingsfrom 7250 newborns in the first step 598 ( 8.2% ) and 682 ( 9.4% ) ears ( right and left , respectively ) failed . in the second step 51 ( 0.7% ) and 58 ( 0.8% ) ears ( right and left , respectively ) failed . 
 consanguinity and route of delivery had significant effect on the frequency of hearing loss.conclusionthe overall frequency of congenital hearing loss in this study was found high .