Determinants of preterm infants' language environment in the neonatal intensive care unit Open Access

Abstract

 Background/Objective: Brain development is shaped by early sensory experiences, including exposure to language and parent-infant interactions. However, preterm infants spend the first months of their life in the neonatal intensive care unit (NICU) where language exposure and parent-infant interactions may be limited. This study sought to characterize preterm infants’ language environment and identify sociodemographic, clinical, environmental, and maternal psychological factors that predict language exposure and parental presence in the NICU.

Methods: Using a cross-sectional study design, sixty-six infants born <38 gestational weeks who were between 32-40 weeks corrected gestational age were recruited at two level III NICUs. The auditory environment was assessed for 48 consecutive hours using digital language processors and independent variables were collected through surveys, medical record abstraction, and observations.  Duration of parent visits were collected from visitation logs. Negative binomial and gamma regression were performed on word count and meaningful speech, respectively. A general linear model was estimated to identify predictors of parent visits.

Results: The majority of the auditory environment was composed of silence and electronic noise, with little language exposure (3.61 + 2.78%). Infants were exposed to an average of 304 words per hour. Infants with high parent visitation (>37%) were exposed to 1.84 times more words and 34% more meaningful speech than infants with low parent visitation (p<0.001). Each additional corrected gestational week increased both word count and meaningful speech by 13% (p<0.001). Preterm infants in open bay areas and on oscillators/ventilators were exposed to 27% and 43% less meaningful speech, respectively (p<0.03). The number of children at home, neurological comorbidity, surgical history, and perceived stressfulness of the NICU each had large main effects on parent visitation while room type and surgical history had a large interaction effect on parent visitation (p<0.04). These predictors accounted for 65.8% of the variance in parental presence.

Conclusion: Language represented a small percentage of auditory stimuli and was most strongly predicted by parent visits. Understanding factors that predict language exposure and parent visitation can help clinicians and researchers develop interventions and design NICUs that encourage parental presence, and thus improve preterm infants’ neurodevelopmental and academic trajectory. 

Table of Contents

Chapter 1—Introduction ………………………………………………………………….1

           Figure 1.1: Theoretical Framework………………………………………….........6

           Figure 1.2: LENA Digital Language Processor………………………………….20

           Table 1.1: Inclusion/Exclusion Criteria………………………………………….26

           Table 1.2: Data Sources………………………………………………………….28

Chapter 2—Influence of Language Nutrition on Children’s Language and Cognitive Outcomes: An Integrated Review……………………………………………………….51

Chapter 3—Determinants of preterm infants’ language environment in the neonatal intensive care unit…122

           Table 3.1: Demographics of Sample……………………………………………144

           Table 3.2: Descriptive Statistics for Clinical Variables………………………...145

Table 3.3: Descriptive Statistics for Environmental/Maternal Psychological Factors……147

           Table 3.4: Auditory Exposures in the NICU…………………………………...148

           Table 3.5: Predictors of Adult Word Count…………………………………….149

           Table 3.6: Predictors of Meaningful Speech……………………………………150

           Figure 3.1: Estimated Marginal Means of Word Count by Parent Visits………151

           Figure 3.2: Estimated Marginal Means for Meaningful Speech………………..152

Chapter 4—Predictors of parental presence in the neonatal intensive care unit………..160

           Table 4.1: Independent Variables Considered as Predictors of Parent Visits…..181

           Table 4.2: Demographics of Sample……………………………………………183

           Table 4.3: Clinical Characteristics of Sample…………………………………..184

           Table 4.4: Parameter Estimates for General Linear Model…………………….185

           Table 4.5: Estimated Marginal Means of Parent Visits by Predictor…………..186

Figure 4.1: Estimated Marginal Means for Interaction Effect between Room Type and Surgical History……………187

Chapter 5—Conclusion…………………………………………………………………194

About this Dissertation

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School	Laney Graduate School
Department	Nursing
Degree	Ph.D.
Submission	Dissertation
Language	English
Research field	Health Sciences, Nursing
Keyword	preterm infants auditory environment language exposure neonatal intensive care unit parent visits
Committee Chair / Thesis Advisor	Dunlop, Anne, Emory University Williams, Bryan, Emory University
Committee Members	Close, Sharron, Emory University Brennan, Patricia, Emory University

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