The influence of gestational age on auditory development in preterm babies

Abstract

The incidence of hearing loss in population of prematurely born babies is twenty times higher (2-4 per 1000) than in well babies population (1-3 per 1000) due to numeorus risk factors. Although early birth is not a risk factor for hearing loss per se, the number of risk factors is in strong correlation with gestational age (Nikolić, 2016). Hearing loss is not allways present at birth, but it could be developed over first years of life as well. Progressive hearing loss could be missed through neonatal hearing screening, so that further monitoring of auditory function is mandatory in population of preterm babies (JCIH, 2007). The goal of this study was to establish the impact of gestational age on auditory development in preterm babies. The study has been conducted in Institute for neonatology in Belgrade, which is the referent hospital for treatment and follow-up of prematurely born babies. The group consisted of 150 prematurely born babies of both genders, 85 girls (56.7%) and 65 boys (43.3%)., which made gender neutral sample (χ2 = 2.67, df = 1, p = .12). The babies were born between 25. and 37. gestational week, with average gestational age of 31.87 weeks (Mdn = 32.5, SD = 2.67). The instrument for auditory assessment was LittlEars® Auditory Questionnaire (Tsiakpini et al, 2004), which is widely implemented for assessment of auditory development in preverbal phase. Previous studies have proven high correlation between scores and age, which implies that it is a good instrument for measurement of age related auditory behavior (Coninx et al., 2009; Nikolić, 2016; Tsiakpini et al., 2004; Weichbold, Tsiakpini, Coninx, & D`Haese, 2005). The data on auditory behavior of babies were summoned from parents at corrected age of 3, 6, 9 and 12 months for each baby. The data were analyzed using descriptive analysis, inferrential statistics and hyerachy multivariatt linear modelling. The influence of gestational age on LittlEars® scale score have shown moderate positive correlation Statistically significant correlation was found at 3 and 12 months corrected age (3 months - rs = .21, p = .01; 12 months - rs = .22, p = .01), which implies possibility of slower auditory development in babies with lower gestational age. The scores obtained at 6 and 9 months corrected age have shown positive correlation without statistical significance (6 months - rs = .16, p = .05; 9 months - rs = .15, p = .07). Further analysis have shown the impact of gestational age on auditory development, taking both calendary and corrected age of preterm babies into consideration. The results have shown considerable effect of gestational age on initial auditory achievement (χ2(128) = 199.94, p < .001), as well as on the pace of subsequent auditory developmentt (χ2(128) = 156.11, p = .046). The results have shown that each week of gestation adds 0.39 points to the initial auditory achievement and 0.41 points to the dynamics of auditory development, during the first year of life in preterm babies (corrected age). It is of utmost importance to determine criteria for follow-up of infants with risk factors for early or progressive hearing loss to develop quality early hearing detection and intervention (EHDI) program. Our study has shown that gestational age could significantly affect auditory development and help define precise criteria for typical auditory achievements of prematurely born babies.