Understanding Early Development of Infants and Toddlers

Understanding Early Development: A Biopsychosocial Perspective on Infant and Toddler Functioning

The goal of this observational study is to analyze early development in infants and young children from a biopsychosocial perspective, with a particular focus on cognitive, language, motor, social-emotional, and adaptive functioning during the first years of life.

The study will include infants and young children from 16 days of age up to 42 months of age, assessed during a single diagnostic session conducted by qualified specialists. The developmental assessment will include standardized diagnostic tasks and direct observation of behavior in the form of play and natural interaction, carried out in the presence of a parent or legal guardian.

In addition, information regarding the child's everyday functioning will be collected from parents or caregivers using standardized questionnaires, including data on social-emotional competencies, communication, and adaptive skills.

The main research questions addressed by this study are:

What is the developmental profile of infants and young children in the first years of life?

What relationships exist between different domains of early development within a biopsychosocial model of child functioning?

Can specific developmental patterns be identified that indicate an increased risk of developmental difficulties in early childhood?

How does age differentiate the structure and variability of developmental functioning across assessed domains?

The study is non-invasive and observational in nature. Data will be analyzed exclusively in aggregated form and will contribute to a better understanding of early child development as well as to the development of norms and tools supporting early diagnosis and developmental intervention.

Study Overview

• Status: Recruiting
• Conditions: Child Development; Infant Development; Early Childhood Development
• Intervention / Treatment: Diagnostic test: Psychological developmental assessment

• Study Type: Observational
• Enrollment (Estimated): 1200

Contacts and Locations

• Study Contact: Name: Rafał Nowicki, M.A.; Phone Number: +48509805591; Email: nowicki@pracowniatestow.pl

Study Locations

• Poland
  • Pomeranian Voivodeship
    • Gdansk, Pomeranian Voivodeship, Poland, 80-239
      • Recruiting
      • Laboratory of Psychological and Educational Tests
      • Contact: Rafał Nowicki, M.A.; Phone Number: +48509805591; Email: nowicki@pracowniatestow.pl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Infants and young children aged 16 days to 42 months, including children with typical development and children with increased developmental risk.

Description

Inclusion Criteria:

• Infants and young children aged from 16 days to 42 months at the time of assessment.
• Participation of a parent or legal guardian able to provide informed consent.
• Child's ability to participate in a standardized developmental assessment appropriate for age and developmental level.
• Availability of basic medical and perinatal information provided by parents or caregivers.
• Assignment to one of the predefined study cohorts based on medical history and developmental status:

children from the general population (control group), children with developmental delay, children with confirmed genetic conditions, children born preterm between 33 and 37 weeks of gestation, children born before 33 weeks of gestation, children with a diagnosis of cerebral palsy.

Exclusion Criteria:

• Severe acute medical condition at the time of assessment preventing participation in the psychological evaluation.
• Uncorrected severe sensory impairments (e.g., profound visual or hearing impairment) that preclude valid administration or interpretation of the developmental assessment.
• Medical instability or conditions requiring immediate intensive medical care.
• Lack of informed consent from a parent or legal guardian.
• Inability of the parent or caregiver to provide reliable information required for questionnaire-based assessment.

Study Plan

How is the study designed?

Number of groups / cohorts

6

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Control Group; Children without identified developmental delays, genetic conditions, or major perinatal complications, assessed as part of the general population.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.
Developmental Delay; Children with identified developmental delay based on prior clinical assessment or referral information, without a confirmed specific genetic diagnosis.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.
Genetic Conditions; Children with confirmed genetic conditions associated with developmental risk, based on medical documentation provided by parents or caregivers.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.
Moderate to Late Preterm; Children born preterm between 33 and 37 weeks of gestational age. This group includes infants and toddlers with a history of moderate to late prematurity, without severe neonatal complications requiring classification as extremely preterm.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.
Extremely Preterm; Children born before 33 weeks of gestational age. This group includes infants and toddlers with a history of extreme prematurity, associated with increased risk for developmental difficulties across multiple domains.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.
Cerebral Palsy; Children with a diagnosis of cerebral palsy documented in medical records. This group includes children with motor impairment of neurological origin, potentially accompanied by cognitive, language, or adaptive difficulties.	Diagnostic test: Psychological developmental assessment; All participants undergo a standardized psychological developmental assessment conducted by trained specialists. The assessment includes structured diagnostic tasks and direct observation of the child's behavior during play and natural interaction, carried out in the presence of a parent or legal guardian. In addition, parents or caregivers complete standardized questionnaires assessing the child's social-emotional functioning and adaptive behavior. No experimental intervention or therapeutic procedure is applied.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cognitive development	Cognitive functioning assessed using the Cognitive Scale of the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4). The scale evaluates early cognitive abilities, including sensory-motor processing, exploration and manipulation, object relations, memory, problem solving, and early executive functioning. Data will be reported as a Composite Score ranging from 40 to 160, where higher scores indicate better cognitive development.	Baseline
Language Development	Language functioning assessed using the Language Scale of the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4), including receptive and expressive communication abilities appropriate to the child's developmental level. Data will be reported as a Composite Score ranging from 40 to 160, where higher scores indicate better language development.	Baseline
Motor Development	Motor functioning assessed using the Motor Scale of the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4), including fine and gross motor skills related to coordination, posture, locomotion, and motor planning. Data will be reported as a Composite Score ranging from 40 to 160, where higher scores indicate better motor development.	Baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Social-emotional functioning	Social-emotional development assessed using the Social-Emotional Scale of the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4), based on parent-reported information regarding emotional regulation, social engagement, communication of needs, and relationship development. Data will be reported as a Scaled Score ranging from 1 to 19, where higher scores indicate better performance.	Baseline
Adaptive behavior functioning	Adaptive behavior assessed using the Adaptive Behavior Scale of the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4), based on parent or caregiver report of the child's everyday functional skills in communication, daily living skills, and socialization. Data will be reported as a Scaled Score ranging from 1 to 19, where higher scores indicate better performance.	Baseline

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Socio-demographic data	Author-designed socio-demographic questionnaire completed by parents or caregivers, including information on the child's sex, month and year of birth, gestational age at birth, place and region of residence, parental education level and selected perinatal characteristics.	Baseline

Collaborators and Investigators

• Sponsor: Bartosz M. Radtke
• Investigators: Principal Investigator: Urszula Sajewicz-Radtke, Ph.D., Laboratory of Psychological and Educational Tests; Study Director: Bartosz M Radtke, Ph.D., Laboratory of Psychological and Educational Tests; Principal Investigator: Ariadna Łada-Maśko, Ph.D., Laboratory of Psychological and Educational Tests

Study record dates

Study Major Dates

• Study Start (Actual): January 2, 2025
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: February 11, 2026
• First Submitted That Met QC Criteria: February 11, 2026
• First Posted (Actual): February 18, 2026

Study Record Updates

• Last Update Posted (Actual): February 23, 2026
• Last Update Submitted That Met QC Criteria: February 19, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Cognitive development; Motor development; Neurodevelopment; Early development; Infant development; Language development; Social-emotional development; Adaptive behavior; Toddler development
• Other Study ID Numbers: 2026/PTPiP/1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No