Predictors of early vocabulary growth in children born preterm and full term: A study of processing speed and medical complications

Early language processing efficiency and pre-literacy outcomes in children born full term and preterm

Language processing efficiency-that is, the skill at processing language in real time-assessed in toddlerhood is associated with later language outcomes in children born full term (FT) and preterm (PT) during school age. No studies to date have assessed patterns of relations between early language processing efficiency and pre-literacy skills, such as print knowledge and phonological awareness, and whether relations are similar in FT and PT children. In this study, participants (N = 94, 49 FT and 45PT) were assessed in the looking-while-listening (LWL) task at 18 months of age (corrected for degree of prematurity), deriving measures of processing speed and accuracy. At 4½ years of age, children were assessed on standardized tests of print knowledge, phonological awareness, and expressive language. Processing speed and accuracy predicted both pre-literacy outcomes (r2 change = 7.8%-19.5%, p < .01); birth group did not moderate these effects. Relations were significantly reduced when controlling for expressive language. Thus, early language processing efficiency supports later expressive language abilities, which in turn supports developing pre-literacy skills. Processing speed and phonological awareness were also directly related, indicating an independent role for processing speed in literacy development. Mediation effects were not moderated by birth group, suggesting a similar developmental pathway in FT and PT children.

The Synergistic Effects of Preterm Birth and Parent Gender on the Linguistic and Interactive Features of Parent-Infant Conversations

PURPOSE

To investigate the language environments experienced by preterm-born infants, this study compared the linguistic and interactive features of parent-infant conversations involving 2-year-old preterm- and term-born infants. The study also explored how mother-infant and father-infant conversations may be differentially affected by preterm/term birth status.

METHOD

Twenty-two preterm-born (< 37 weeks' gestation) and 25 term-born (≥ 37 weeks' gestation) 2-year-old infants engaged in dyadic mother/father-infant free-play interactions that were transcribed to quantify the linguistic (parental volubility, speech rate, lexical diversity, and morphosyntactic complexity) and interactive (infant/parent responsiveness, turn-taking, and conversational balance) features of parent-infant conversations. Language, cognitive, socioemotional, and executive function skills were assessed via standardized tools.

RESULTS

Compared to the term group, the preterm group was characterized by lower maternal speech rate, parental lexical diversity, and parent-infant turn-taking, as well as greater mother-infant conversational balance. The preterm group presented poorer language and executive function skills when compared to the term group.

CONCLUSIONS

Both similarities and differences exist between the language environments of preterm and term groups. Similarities may be due to the partial developmental catch-up of preterm-born infants (cognitive and socioemotional skills) and parental scaffolding. Differences may partly reflect a parental adaptation to the language and executive function difficulties of preterm-born infants. These findings suggest that researchers/clinicians should appraise the language environment with respect to the unique developmental needs of preterm/term-born infants. Future research directions are provided to advance a more holistic characterization of the language environment and a deeper understanding of the developmental significance of preterm-term differences in such environments.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25021931.

Parent-infant conversations are differentially associated with the development of preterm- and term-born infants

Preterm birth is a risk factor for language difficulties. To better understand the language development of preterm-born infants, the current study investigated the concurrent associations between parent-infant conversations and the development of 22 preterm-born and 25 term-born infants at 2 years of age. Conversations occurring during mother/father-infant free-play interactions were analyzed to characterize features of parental speech (volubility, speech rate, lexical diversity, and morphosyntactic complexity) and parent-infant exchanges (parent responsiveness, turn-taking, and conversational balance). The infants' language development (receptive communication and expressive communication) and non-language development (cognitive, social-emotional, and executive function) was assessed using standardized measures. Parent-infant conversations were associated with both language and non-language development. This suggests that parent-infant conversations may support language development directly and/or through advancing non-language skills that could promote language learning. The associations between parent-infant conversations and development varied as a function of birth status (preterm or term). This finding may signal the operation of different developmental processes within preterm- and term-born groups. Finally, infant development was differentially associated with mother-infant and father-infant conversations. This may point to the distinct contributions made by mothers and fathers to the development of both preterm- and term-born infants. To optimize language outcomes, these findings indicate that families should be guided to tailor parent-infant conversations to the unique developmental needs and processes of preterm-born infants. Families should also be supported to leverage the distinct developmental contributions of mothers and fathers. Future recommendations are made regarding how to investigate the proposed preterm-term differences in language development processes and the differential developmental contribution of mothers and fathers.

Parental cognitive stimulation in preterm-born children's neurocognitive functioning during the preschool years: a systematic review

In the United States, survival rates for preterm neonates (<37 weeks of gestation) have tripled in recent years. In parallel, preterm-born children show poorer performance in neurocognitive functioning compared to their full-term peers (≥39 weeks of gestation), and biological models predicting preterm-born children's neurocognitive performance have been met with limited success, highlighting a need to focus on environmental factors. Thus, this systematic review examines the literature on parental cognitive stimulation in relation to preterm-born children's neurocognitive outcomes. Studies were considered for inclusion if they included a sample of preterm-born children, included a measure of parental cognitive stimulation, and included a measure of child neurocognitive performance. The databases searched were PubMed, PsychINFO, CINAHL, ProQuest, and Scopus. Eight studies were included (44 unique associations). Findings suggest that preterm-born children's language skills might be open to a wide range of qualitative and quantitative features of parental cognitive stimulation. Our findings suggest that parental cognitive stimulation matters for preterm-born children's neurocognitive performance. Future experiential models should examine the mechanistic roles of cognitive stimulation in relation to narrowed neurocognitive outcomes to better inform possible prevention and intervention efforts. IMPACT: This systematic review examines the literature on parental cognitive stimulation in relation to preterm-born children's neurocognitive outcomes. Our review demonstrates that preterm-born children's language skills might be open to a wide range of qualitative and quantitative features of parental cognitive stimulation. The emphasis on environmental factors might ultimately better inform possible prevention and intervention efforts for children at risk as they transition to formal schooling.

Language environment and parent-infant close contact in neonatal care and emerging lexical abilities of very preterm children-a longitudinal study

AIM

This longitudinal study investigated associations between language environment and parent-infant close contact in the neonatal intensive care unit (NICU) and preterm children's lexical abilities.

METHODS

NICU language environment of 43 very preterm infants (born<32 gestational weeks) was measured with the Language Environment Analysis System (LENA; variables: number of adult words, conversational turns, and child vocalisations). Parent-infant close contact (holding and skin-to-skin contact) in the NICU was reported using parental closeness diaries. At 15 and 18 months' corrected age, lexical development was measured with screening methods, and eye tracking-based lexical processing was assessed at 18 months. N varied between 29 and 38 in different outcome measures.

RESULTS

LENA measured conversational turns and child vocalisations, and parent-infant close contact associated positively with lexical development (r = 0.35-0.57). High numbers of NICU adult words associated negatively with lexical processing (r = -0.38- -0.40). In regression models, conversational turns and parent-infant close contact explained 34%-35% of receptive development.

CONCLUSION

Findings suggest that adult-infant turn taking and parent-infant close contact in the NICU are positively associated with lexical development. High numbers of overheard words in the NICU may not favour later lexical processing. Further research is warranted on the significance of NICU language environment on later lexical abilities.

Probing the Impact of Prematurity on Segmentation Abilities in the Context of Bilingualism

Infants born prematurely are at a high risk of developing linguistic deficits. In the current study, we compare how full-term and healthy preterm infants without neuro-sensorial impairments segment words from fluent speech, an ability crucial for lexical acquisition. While early word segmentation abilities have been found in monolingual infants, we test here whether it is also the case for French-dominant bilingual infants with varying non-dominant languages. These bilingual infants were tested on their ability to segment monosyllabic French words from French sentences at 6 months of (postnatal) age, an age at which both full-term and preterm monolinguals are able to segment these words. Our results establish the existence of segmentation skills in these infants, with no significant difference in performance between the two maturation groups. Correlation analyses failed to find effects of gestational age in the preterm group, as well as effects of the language dominance within the bilingual groups. These findings indicate that monosyllabic word segmentation, which has been found to emerge by 4 months in monolingual French-learning infants, is a robust ability acquired at an early age even in the context of bilingualism and prematurity. Future studies should further probe segmentation abilities in more extreme conditions, such as in bilinguals tested in their non-dominant language, in preterm infants with medical issues, or testing the segmentation of more complex word structures.

A Comparison of the Clinical Presentation of Preterm Birth and Autism Spectrum Disorder: Commonalities and Distinctions in Children Under 3

Premature infants and infants later diagnosed with autism spectrum disorder (ASD) share many commonalities in clinical presentations. However, prematurity and ASD also have differences in clinical presentation. These overlapping phenotypes can lead to misdiagnoses of ASD or missing a diagnosis of ASD in preterm infants. We document these commonalities and differences in various developmental domains with the hope of aiding in the accurate early detection of ASD and timely intervention implementation in children born premature. Given the degree of similarities in presentation, evidence-based interventions designed specifically for preterm toddlers or toddlers with ASD may ultimately aid both populations.

Associations between early efficiency in language processing and language and cognitive outcomes in children born full term and preterm: similarities and differences

Associations between children's early language processing efficiency and later verbal and non-verbal outcomes shed light on the extent to which early information processing skills support later learning across different domains of function. Examining whether the strengths of associations are similar in typically developing and at-risk populations provides an additional lens into the varying routes to learning that children may take across development. In this follow-up study, children born full-term (FT, n = 49) and preterm (PT, n = 45, ≤32 weeks gestational age, birth weight <1800 g) were assessed in the Looking While Listening (LWL) task at 18 months (corrected for degree of prematurity in PT group). This eye-tracking task assesses efficiency of real-time spoken language comprehension as accuracy and speed (RT) of processing. At 4 ½ years, children were assessed on standardized tests of receptive vocabulary, expressive language, and non-verbal IQ. Language processing efficiency was associated with both language outcomes (r²-change: 7.0-19.7%, p < 0.01), after covariates. Birth group did not moderate these effects, suggesting similar mechanisms of learning in these domains for PT and FT children. However, birth group moderated the association between speed and non-verbal IQ (r²-change: 4.5%, p < 0.05), such that an association was found in the PT but not the FT group. This finding suggests that information processing skills reflected in efficiency of real-time language processing may be recruited to support learning in a broader range of verbal and non-verbal domains in the PT compared to the FT group.

Eye tracking based assessment of lexical processing and early lexical development in very preterm children

BACKGROUND

Associations between lexical processing and lexical development during the second year of life have been little studied in preterm children.

AIMS

To evaluate associations between lexical processing at 18 months and lexical development between 12 and 18 months in very preterm children.

STUDY DESIGN

Correlational study.

SUBJECTS

25 Finnish-speaking children born <32 gestational weeks.

OUTCOME MEASURES

Lexical processing (reaction time RT; correct looking time CLT) was measured with an eye tracking technology-based task at 18 months' corrected age. Lexical development was measured longitudinally at 12-, 15- and 18-months' corrected age using the following screening instruments: the short form version of the MacArthur Communicative Development Inventories and the Communication and Symbolic Behavior Scale: Infant-Toddler Checklist.

RESULTS

The longer the RT of the child, the weaker expressive skills the child had at 12 and 15 months (correlations coefficient values -0.45 to -0.51). The more the child looked at the target image compared to the distractor (CLT), the stronger expressive skills the child had at 18 months (r = 0.45-0.52). A linear regression model with RT and gender as independent variables explained 33 % of the variance in lexical skills at 18 months. A model with CLT explained 40 % of expressive skills at 18 months.

CONCLUSIONS

Lexical processing at 18 months was associated with expressive lexical development in very preterm children. The results suggest eye tracking technology based methods may have utility in the assessment of early lexical growth in preterm children, although further research is needed to assess psychometric properties and predictive value of the method.

Generalized Slowing Rather Than Inhibition Is Associated With Language Outcomes in Both Late Talkers and Children With Typical Early Development

Purpose While most of the children who are identified as late talkers at the age of 2 years catch up with their peers before school age, some continue to have language difficulties and will later be identified as having developmental language disorder. Our understanding of which children catch up and which do not is limited. The aim of the current study was to find out if inhibition is associated with late talker outcomes at school age. Method We recruited 73 school-aged children (ages 7-10 years) with a history of late talking (n = 38) or typical development (n = 35). Children completed measures of language skills and a flanker task to measure inhibition. School-age language outcome was measured as a continuous variable. Results Our analyses did not reveal associations between inhibition and school-age language index or history of late talking. However, stronger school-age language skills were associated with shorter overall response times on the flanker task, in both congruent and incongruent trials. This effect was not modulated by history of late talking, suggesting that a relationship between general response times and language development is similar in both children with typical early language development and late talkers. Conclusions Inhibition is not related to late talker language outcomes. However, children with better language outcomes had shorter general response times. We interpret this to reflect differences in general processing speed, suggesting that processing speed holds promise for predicting school-age language outcomes in both late talkers and children with typical early development. Supplemental Material https://doi.org/10.23641/asha.14226722.

Prevalence of Language Delay among Healthy Preterm Children, Language Outcomes and Predictive Factors

Language delay (LD) and its relationship with later language impairment in preterm children is a topic of major concern. Previous studies comparing LD in preterm (PT) and full-term (FT) children were mainly carried out with samples of extremely preterm and very preterm children (sometimes with additional medical problems). Very few of them were longitudinal studies, which is essential to understand developmental relationships between LD and later language impairment. In this study, we compare the prevalence of LD in low-risk preterm children to that of FT children in a longitudinal design ranging from 10 to 60 months of age. We also analyze which variables are related to a higher risk of LD at 22, 30 and 60 months of age. Different language tests were administered to three groups of preterm children of different gestational ages and to one group of full-term children from the ages of 10 to 60 months. ANOVA comparisons between groups and logistic regression analyses to identify possible predictors of language delay at 22, 30 and 60 months of age were performed. The results found indicate that there were practically no differences between gestational age groups. Healthy PT children, therefore, do not have, in general terms, a higher risk of language delay than FT children. Previous language delay and cognitive delay are the strongest and longest-lasting predictors of later language impairment. Other factors, such as a scarce use of gestures at 10 months or male gender, affect early LD at 22 months of age, although their effect disappears as children grow older. Low maternal education appears to have a late effect. Gestational age does not have any significant effect on the appearance of LD.

Improving the robustness of infant lexical processing speed measures

Visual reaction times to target pictures after naming events are an informative measurement in language acquisition research, because gaze shifts measured in looking-while-listening paradigms are an indicator of infants' lexical speed of processing. This measure is very useful, as it can be applied from a young age onwards and has been linked to later language development. However, to obtain valid reaction times, the infant is required to switch the fixation of their eyes from a distractor to a target object. This means that usually at least half the trials have to be discarded-those where the participant is already fixating the target at the onset of the target word-so that no reaction time can be measured. With few trials, reliability suffers, which is especially problematic when studying individual differences. In order to solve this problem, we developed a gaze-triggered looking-while-listening paradigm. The trials do not differ from the original paradigm apart from the fact that the target object is chosen depending on the infant's eye fixation before naming. The object the infant is looking at becomes the distractor and the other object is used as the target, requiring a fixation switch, and thus providing a reaction time. We tested our paradigm with forty-three 18-month-old infants, comparing the results to those from the original paradigm. The Gaze-triggered paradigm yielded more valid reaction time trials, as anticipated. The results of a ranked correlation between the conditions confirmed that the manipulated paradigm measures the same concept as the original paradigm.

Neonatal white matter tract microstructure and 2-year language outcomes after preterm birth

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Preterm infant white matter tracts uniquely predict later toddler language.

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Neonatal medical history moderates posterior corpus callosum–language relations.

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Different associations by tract may relate to brain maturation and medical history.

Aim

To determine whether variability in diffusion MRI (dMRI) white matter tract metrics, obtained in a cohort of preterm infants prior to neonatal hospital discharge, would be associated with language outcomes at age 2 years, after consideration of age at scan and number of major neonatal complications.

Method

30 children, gestational age 28.9 (2.4) weeks, underwent dMRI at mean post menstrual age 36.4 (1.4) weeks and language assessment with the Bayley Scales of Infant Development–III at mean age 22.2 (1.7) months chronological age. Mean fractional anisotropy (FA) and mean diffusivity (MD) were calculated for 5 white matter tracts. Hierarchical linear regression assessed associations between tract FA, moderating variables, and language outcomes.

Results

FA of the left inferior longitudinal fasciculus accounted for 17% (p = 0.03) of the variance in composite language and FA of the posterior corpus callosum accounted for 19% (p = 0.02) of the variance in composite language, beyond that accounted for by post-menstrual age at scan and neonatal medical complications. The number of neonatal medical complications moderated the relationship between language and posterior corpus callosum FA but did not moderate the association in the other tract.

Conclusion

Language at age 2 is associated with white matter metrics in early infancy in preterm children. The different pattern of associations by fiber group may relate to the stage of brain maturation and/or the nature and timing of medical complications related to preterm birth. Future studies should replicate these findings with a larger sample size to assure reliability of the findings.

Developmental Dimensions in Preterm Infants During the 1st Year of Life: The Influence of Severity of Prematurity and Maternal Generalized Anxiety

BACKGROUND

The literature has recognized premature birth as a risk factor for infant development and maternal anxiety. This study investigated the impact of the severity of birth weight, as well as of maternal anxiety at 3 months of infants' corrected age, on infants' outcomes during the 1st year postpartum. Moreover, it described the longitudinal trajectories of developmental outcomes, additionally exploring the impact of anxiety.

METHODS

The study compared 147 mothers and their 147 newborns, differentiated in 25 Extremely Low Birth Weight (ELBW), 41 Very Low Birth Weight (VLBW), and 81 Full-Term (FT) infants. At 3, 9, and 12 months (corrected age in the case of preterm infants) the level of infants' development was investigated according to the 5 quotients (Locomotor, Personal and Social, Hearing and Language, Eye-hand Co-ordination and Performance) of the Griffiths Mental Development Scales (GMDS-R). During the assessment of 3 months, mothers fulfilled Penn State Worry Questionnaire (PSWQ) to evaluate the presence of generalized anxiety.

RESULTS

Among the 5 GMDS-R quotients, significant effect of severity of birth weight emerged only for Performance quotient: preterm infants (ELBW at 3 months; VLBW at 12 months) showed lower scores than FT ones. Moreover, this quotient decreased from 3 to 9 and to 12 months for VLBW and FT infants, while it was stable for ELBW ones. A significant interaction between severity of birth weight and maternal anxiety emerged for Hearing and Language and Locomotor quotients. In the first case, scores for ELBW infants, independently from maternal anxiety, decreased from 9 to 12 months. The same results emerged for VLBW infants, in the case of non-anxious mothers. Regarding Locomotor quotient, mean scores decreased from 3 to 9 and to 12 months for all groups in the case of non-anxious mothers. Conversely, when mothers were anxious, this decrease emerged only for VLBW infants. Lastly, ELBW, VLBW and FT showed difference in the growth and slope of the trajectories of different quotients.

CONCLUSION

The severity of birth weight for preterm infants, also in interaction with maternal anxiety, had significant and specific impact on different dimensions of infants' development. Clinical implications of these results underline the need for individualized interventions.