Bayley-III scales at 12 months of corrected age in preterm infants: Patterns of developmental performance and correlations to environmental and biological influences.
Low Bayley-III scores at 12 months corrected age flag real, lasting delays in preterm infants—act on them immediately.
01Research in Context
What this study did
Doctors gave the Bayley-III to 123 preterm babies at 12 months corrected age. They looked at cognitive, language, motor, social-emotional, and adaptive scores.
They also recorded medical facts: how early the baby was born, days on oxygen, brain bleeds, and parent education.
What they found
More than half of the babies scored below the 50th percentile on every scale except social-emotional. Parents rated their babies’ social-emotional skills higher than the examiner did.
The more medical risks a baby had, the lower the scores. Oxygen use and brain bleeds were the strongest predictors.
How this fits with other research
Yaari et al. (2018) tracked the same babies longitudinally and showed the gaps widen by 18 months. Their Mullen scores kept dropping, proving the Bayley-III snapshot was an early warning, not a one-off bad day.
Kuang et al. (2025) reused BSID-III trajectories and built a model that can rule out ASD risk with 93.6 % certainty. The low Bayley-III scores we see here are the first data points in that risk pipeline.
Kretschmer et al. (2014) found normal phoneme hearing but delayed stress-pattern detection in preterm infants. The low Bayley-III language scores here match those hidden auditory processing lags.
Why it matters
If you test a preterm baby at 12 months corrected age and see low cognitive, language, or motor scores, don’t wait. Use the score to start referral paperwork right away. The delay is real, it persists, and early intervention can begin while the brain is most plastic.
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Join Free →Plot each preterm baby’s Bayley-III score on the growth chart; if any domain is <25th percentile, fax the early-intervention referral before lunch.
02At a glance
03Original abstract
BACKGROUND AND AIMS: Premature infants are at high risk for neurodevelopmental impairment (NDI) even in the absence of known brain complications of prematurity. Evaluation of the effectiveness of therapeutic interventions in association to neurodevelopmental outcome is required to improve or prevent the neurodevelopmental consequences of prematurity. The Bayley-III is currently the most commonly applied measurement tool for assessing early development both in clinical practice and research settings. OBJECTIVE: To evaluate the relationship between known risk factors and early performance on the Bayley Scales of Infant Development-Third Edition at 12 months adjusted age in premature infants. METHODS: Prospective study in a cohort of premature infants with gestational age ≤32 weeks, who underwent comprehensive developmental assessment using the five domains of Bayley Scales, cognitive, language, motor, social emotional and adaptive behavior at 12 months corrected age. Developmental scores were evaluated in relation to environmental influences, therapeutic interventions or practices and complications of prematurity. RESULTS: Composite and Subscale scores for the cognitive, language and motor scales were below the 50th percentile, with no significant differences among them. Scores for the social-emotional and adaptive behavior, which are derived from the parent-report questionnaires, were near the average and significantly higher than the scores derived by the examiners. Multiple regression analyses showed that blood transfusions, apart from severely abnormal head ultrasound, gender, being small for gestational age and duration of invasive mechanical ventilation and oxygen administration were consistently related to neurodevelopmental outcome. CONCLUSIONS: Bayley-III assessments are important for getting early information about development following premature birth. Parents may overestimate children's performance. Neurodevelopmental outcome is related to several environmental, biological or medical conditions associated with prematurity. Adoption of therapeutic strategies targeting known neonatal risk factors could positively affect neurodevelopmental outcome.
Research in developmental disabilities, 2015 · doi:10.1016/j.ridd.2015.07.014