Newborn Screening

Universal newborn hearing screening, the technologies that power it, the 1-3-6 benchmarks that pace it, and the risk register that catches what a one-off screen cannot.

Why universal, and why at birth

Permanent congenital hearing loss affects roughly one to two newborns per thousand — common enough, and consequential enough, to justify screening every baby rather than only those with risk factors. Targeted screening alone misses about half of affected infants, because most are born into families with no history and no obvious risk[3]. Universal newborn hearing screening (UNHS) is now standard of care in most high-income systems[1].

The two technologies

Screening uses one or both of two objective tests. Otoacoustic emissions (OAEs) probe outer-hair-cell function: a healthy cochlea returns a measurable echo to a click or tone. OAE screening is fast and cheap, but it tests only as far as the cochlea — it is normal in auditory neuropathy spectrum disorder, where the lesion is neural[13]. Automated auditory brainstem response (AABR) presents clicks and uses an algorithm to detect a brainstem response, so it tests the pathway through the auditory nerve and lower brainstem and will flag neural lesions that OAEs miss[6].

Because OAEs miss neural loss, well-baby protocols that screen with OAEs alone are supplemented by AABR for infants at risk of ANSD — in particular any baby who spent time in neonatal intensive care, where hyperbilirubinaemia and hypoxia raise the risk. Most NICU protocols therefore screen with AABR from the outset [1]. Two-stage protocols (re-screen before referral) reduce false-positive referrals and parental anxiety [6].

The 1-3-6 benchmarks

The Joint Committee on Infant Hearing frames the timeline as 1-3-6: screening by 1 month of age, diagnostic audiological confirmation by 3 months, and enrolment in early intervention by 6 months[2]. The 2019 statement keeps these as the minimum and sets a more ambitious aspirational target of 1-2-3 — screen by one month, diagnose by two, intervene by three — reflecting the evidence that earlier is better [1].

The risk register — screening is not a single event

A pass at birth does not exclude later hearing loss. Some losses are progressive, late-onset, or acquired, and mild losses can slip through a screen. The JCIH therefore maintains a list of risk indicators — including congenital cytomegalovirus, a family history of childhood hearing loss, NICU care, certain craniofacial anomalies and syndromes, and bacterial meningitis — that mandate audiological surveillance beyond the newborn screen, regardless of the screening result[1]. Congenital CMV is now the leading non-genetic cause of childhood sensorineural loss and a frequent cause of late-onset, progressive loss, which is why it features so prominently in surveillance. Ongoing developmental monitoring through childhood remains essential [23].