The aim of this study is to investigate the effectiveness the HEP (Homeostasis-Enrichment-Plasticity) approach, which based upon the principles of enriched environment (EE) and ecological theories of development on preterm infants with developmental delay risk.

Thirty-two preterm infants aged 4-10 months will be randomly divided into 2 groups as the HEP intervention group and the Traditional Physical Therapy (TPT) group.

EE-based intervention will be applied to the HEP intervention group, and traditional physiotherapy will be applied to the TPT group for 12 weeks (24 sessions).

The demographic information of the participants will be recorded. The motor and sensory functions of the infants will be evaluated with, the Peabody Developmental Motor Scales (PDMS-2) and the Test of Sensory Functions in Infants™ (TSFI™), respectively. Additionally, the anxiety status of the parents will be evaluated with the Beck Anxiety Inventory (BAI). All evaluations will be done twice, at the end and at the beginning of 12 weeks.

Premature birth is defined by WHO (World Health Organization) as all births occurring before 37 weeks of gestation. The global preterm birth rate for 2014 is estimated at 10.6% (9%-12%), equating to an estimated 14.84 million (12.65 million-16.73 million) live preterm births in 2014.

Preterm birth results in significant healthcare utilization and costs. Families of preterm infants often experience significant psychological and significant psychological and financial difficulties. Preterm infants have an increased risk for social, cognitive, language, sensory processing and motor skill disorders. There are different early intervention methods for preterm infants, and enriched environment (EE)-based intervention is one of the current intervention methods that have been used recently. There are studies showing that EE-based interventions have neurobehavioral benefits and positively affect brain functions and motor development.

There are a limited number of studies on EE-based early intervention methods in the literature, and these studies were conducted in different age and diagnosis groups by applying different intervention methods. Therefore, more studies are needed on this subject.

In this study, it was aimed to contribute to the literature in this field and to investigate the effectiveness of an EE-based intervention on the sensory and motor functions of preterm infants and the emotional state of the family.

Inclusion Criteria:

• To be in corrected age between 4 and 10 months
• To being born 33 weeks and 6 days of gestation and before,
• To absence of any systemic disease, congenital anomaly,
• The family's volunteer to participate regularly in the study process.
• Having abnormal or suspect results on the Denver Developmental Screening Test II

Exclusion Criteria:

• To be born at or after 34 weeks of gestational age
• To having experienced intraventricular bleeding (Grade III and IV),
• To having major vision or hearing problems
• To having medical conditions that prevent active participation in the study (such as oxygen dependence)
• To participate in other experimental rehabilitation studies.