The Infants and Toddlers with Disabilities Program (Part C) of the Individuals with Disabilities Education Act (IDEA) was created in 1986 to enhance the development of infants and toddlers with disabilities, minimize potential developmental delay, and reduce educational costs to our society by minimizing the need for special education services as children with disabilities reach school age.  Part C provides early intervention (EI) services to infants and toddlers aged birth to three with developmental delays or a medical condition likely to lead to a developmental delay. 

Why Intervene Early? 

• Decades of rigorous research show that children’s earliest experiences play a critical role in brain development. The Center on the Developing Child at Harvard University has summarized this research:
• Neural circuits, which create the foundation for learning, behavior and health, are most flexible or “plastic” during the first three years of life. Over time, they become increasingly difficult to change.
• Persistent “toxic” stress, such as extreme poverty, abuse and neglect, or severe maternal depression can damage the developing brain, leading to lifelong problems in learning, behavior, and physical and mental health.
• The brain is strengthened by positive early experiences, especially stable relationships with caring and responsive adults, safe and supportive environments, and appropriate nutrition.
• Early social/ emotional development and physical health provide the foundation upon which cognitive and language skills
• High quality early intervention services can change a child’s developmental trajectory
  

https://developingchild.harvard.edu/guide/what-is-early-childhood-development-a-guide-to-the-science/