## 4 Discussion  
In order to determine the prevalence rate of hearing loss of newborns in the Netherlands, all Dutch well-babies born in 2015-2019 were investigated. A total prevalence rate of 1.23 per 1000 newborns was found for a permanent hearing loss of \(\geq\)40 dB in one or both ears. The prevalence for permanent bilateral hearing loss was 0.76 per 1000 newborns, \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Unilateral HL**} & \multicolumn{2}{c}{**Bilateral HL**} \\ \hline  & \(n\) & \% Diagnosed within 3 Months & \(n\) & \% Diagnosed within 3 Months \\ \hline Moderate & 134 & 84.3 & 391 & 82.1 \\ Severe & 72 & 91.7 & 54 & 85.2 \\ Profound & 172 & 93.0 & 178 & 98.3 \\ Unknown & 6 & 100.0 & 9 & 77.8 \\ \hline Total & 384 & 89.8 & 632 & 86.9 \\ \hline \hline \end{tabular}  
* Data from 5 children are missing because the date of diagnosis is lacking.  
\end{table} 
Table 4: Timeliness of diagnosis categorized by severity of hearing loss 1. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**2015**} & \multicolumn{2}{c}{**2016**} & \multicolumn{2}{c}{**2017**} & \multicolumn{2}{c}{**2018**} & \multicolumn{2}{c}{**2019**} & \multicolumn{2}{c}{**Total**} \\ \hline  & \(n\) & \% & \(n\) & \% & \(n\) & \% & \(n\) & \% & \(n\) & \% & \(n\) & \% \\ \hline
**Normal hearing/HL \textless{} 40 dB** & 311 & 61.5 & 319 & 61.9 & 358 & 65 & 325 & 58.5 & 348 & 62.8 & 1661 & 61.9 \\
**Unilateral HL** & 82 & 16.2 & 68 & 13.2 & 74 & 13.4 & 85 & 15.3 & 77 & 13.9 & 386 & 14.4 \\
**Bilateral HL** & 113 & 22.3 & 128 & 24.9 & 119 & 21.6 & 146 & 26.3 & 129 & 23.3 & 635 & 23.7 \\ \hline
**Total** & 506 & & 515 & & 551 & & 556 & & 554 & & 2682 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Annual diagnostic results after well-baby hearing screening from 2015 to 2019. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Severity** & **Unilateral HL** & \multicolumn{2}{c}{**Bilateral HL**} & \multicolumn{2}{c}{**Total**} \\ \hline  & \(n\) & \% & \(n\) & \% & \(n\) & \% \\ \hline Moderate & 135 & 0.16 & 394 & 0.47 & 529 & 0.63 \\ Severe & 72 & 0.09 & 54 & 0.06 & 126 & 0.15 \\ Profound & 173 & 0.21 & 178 & 0.21 & 351 & 0.42 \\ Unknown & 6 & 0.00 & 9 & 0.00 & 15 & 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Prevalence of hearing loss \(\geq\) 40 dB by severity in the well-baby population of the Netherlands in 2015–2019 (\(n\) = 833,318 children, number (\(n\)) and prevalence (%) per 1000 eligible children). and for unilateral hearing loss, 0.46 per 1000. The current study reported on the data of the well-baby hearing screening program, which includes 98% of all newborns. The remaining 2% of the newborns are screened within the NICU program. Annual reports of the NICU hearing screening program of the same time period as the current study (2015-2019) reveal a prevalence of permanent hearing loss of \(\geq\)40 dB in one or both ears of 20.92 per 1000 NICU babies [17; 18; 19; 20; 21]. Combining our findings with the NICU results over the same time period leads to a prevalence rate of bilateral hearing loss in the complete Dutch newborn population of 1.22 per 1000 children and 0.63 per 1000 for unilateral hearing loss. This number is comparable to other studies reporting the prevalence of permanent hearing loss in newborns [22; 23; 24; 25; 26]. Recently, two meta-analyses reported on the prevalence of permanent hearing loss in newborns worldwide [22; 23]. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [23] reported a prevalence of bilateral hearing loss of 1.33 per 1000 and a prevalence of unilateral hearing loss of 0.78 per 1000 newborns. [PERSON], [PERSON], [PERSON] and [PERSON] [22] reported a prevalence of bilateral permanent hearing loss \(\geq\) 26 dB of 1.1 per 1000 newborns. Included studies were not nationwide and varied in sample size, the definition of hearing loss, quality of audiometric testing, and number of newborns that were lost to follow-up.