Developmental Delays In Children: Causes and Symptoms

Quick Summary

Developmental delays affect approximately 1 in 6 children in the United States and can occur across areas including speech and language, motor skills, cognition, and social-emotional development. When delays affect multiple areas, this is called global developmental delay. Early identification and intervention are the most powerful tools available for supporting children with developmental delays, and in New Jersey, services are available for children from birth to age three at no or low cost through the early intervention program.

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No two children develop at exactly the same pace. There is genuine variation in when children sit, speak their first words, start walking, or engage with peers. This natural variation is why pediatricians talk about ranges rather than single target ages for developmental milestones.

But there is a difference between normal variation and a developmental delay. A developmental delay is not just being a little behind. It is when a child is consistently not reaching milestones expected within the typical developmental range for their age, and when this pattern appears across skills and over time rather than in isolated moments.

Understanding what developmental delays in children are, how they are recognized, what causes them, and what can be done about them is among the most important knowledge a parent can have during the early years. At Innovative Interventions, our multidisciplinary team provides early intervention services across New Jersey to support children with developmental delays and their families.

What Are Developmental Delays in Children?

As Cleveland Clinic describes it, a developmental delay is when a child is slow to reach one or more developmental milestones compared to their peers. These milestones span all areas of development: motor, speech, cognitive, social, and adaptive skills.

It is important to note that a developmental delay is not the same as a developmental disability. A delay means a child is reaching milestones more slowly than expected; with early support, many children with delays catch up to their peers. A developmental disability, by contrast, tends to be a lifelong condition that shapes how the brain functions rather than representing a lag in the pace of development.

When significant delays are present in two or more developmental areas simultaneously, this is called global developmental delay (GDD). According to the CDC, approximately 1 in 6 children in the United States, or 17%, has at least one developmental delay.

Common Types of Developmental Delays

Speech and Language Delays

Speech and language delays are the most common type of developmental delay. They can affect expressive language (what a child says), receptive language (what a child understands), or both. A child who is not babbling by 9 months, not using single words by 16 months, or not combining two words by 24 months may have a speech or language delay.

Speech and language delays do not all look the same. Some children have limited vocabulary but strong comprehension. Others understand very little of what is said to them. Still others speak but are very difficult to understand. Each profile requires a different approach. Learn more about the causes and signs of speech delay in our post on what causes expressive speech delay in toddlers.

Motor Skill Delays

Motor delays can affect gross motor skills (large muscle movements like rolling, sitting, crawling, walking, and running) or fine motor skills (small muscle movements in the hands and fingers). Gross motor delays are frequently addressed through physical therapy, while fine motor delays are typically addressed through occupational therapy.

A child who is not sitting independently by 9 months, not walking by 18 months, or consistently falling more than expected for a walking toddler may have a gross motor delay. Our post on delayed walking in babies provides a detailed look at motor milestones and when to seek evaluation.

Cognitive Delays

Cognitive delays affect a child's ability to think, learn, understand, and solve problems. A child with a cognitive delay may have difficulty following directions, understanding cause and effect, engaging in symbolic play, or acquiring concepts that peers grasp easily. Cognitive delays often co-occur with speech, language, and social delays.

Social and Emotional Delays

Social and emotional development includes the ability to form attachments, engage in back-and-forth interaction, recognize and respond to others' emotions, develop friendships, and manage one's own emotional responses. Delays in this area can affect a child's relationships, behavior, and ability to participate in group settings like preschool.

Adaptive Skill Delays

Adaptive skills are the practical skills of daily life: feeding, dressing, bathing, toileting, and navigating the immediate environment. Children who are significantly behind in adaptive skills relative to their age and cognitive level may benefit from occupational therapy focused on self-care and daily living skills. Visit our occupational therapy services page to learn how we support children in this area.

Signs and Symptoms of Developmental Delays by Age

Signs in Babies (0-12 Months)

• Does not smile socially by 3 months

• Does not track moving objects with eyes by 3 months

• Cannot hold head steady by 4 months

• Does not babble or make consonant sounds by 6-9 months

• Does not respond to name by 9 months

• Does not use gesture (pointing, waving) by 12 months

• Does not pull to stand or attempt walking by 12 months

Signs in Toddlers (1-3 Years)

• Not walking independently by 18 months

• Fewer than 15 words by 18 months or fewer than 50 words by 24 months

• Not combining two words by 24 months

• Difficulty understanding simple instructions

• Not engaging in pretend play by 24-30 months

• Loss of skills previously acquired (regression) at any point

Signs in Preschoolers (3-5 Years)

• Significant difficulty being understood by familiar adults

• Unable to follow two-step directions by age 3

• No interest in other children or significant difficulty with peer interaction

• Cannot run, jump, or climb with coordination similar to peers

• Significant difficulty with self-care tasks expected at the child's age

• Persistent behavioral challenges that go beyond typical developmental behavior

What Causes Developmental Delays in Children?

As Cleveland Clinic notes, researchers do not always know the cause of developmental delays. However, recognized contributing factors include:

• Genetic conditions: Down syndrome, fragile X syndrome, and other chromosomal or genetic differences frequently include developmental delays as part of a broader profile

• Prematurity: Babies born before 37 weeks are at elevated risk for developmental delays in motor, cognitive, and language domains

• Prenatal exposures: Alcohol, certain medications, opioids, and environmental toxins during pregnancy can affect fetal brain development

• Perinatal complications: Oxygen deprivation at birth, birth injury, or very low birth weight can have lasting effects on development

• Hearing or vision impairment: Undetected hearing loss is a significant cause of language delay; vision impairment can affect motor and cognitive development

• Chronic illness: Conditions requiring frequent hospitalization or medical intervention can limit opportunities for typical developmental experience

• Environmental factors: Significant deprivation of language, stimulation, or nurturing caregiving can contribute to developmental delays

• Unknown causes: In many cases, no specific cause is identified despite thorough evaluation

How Developmental Delays Are Diagnosed

Developmental delays are identified through a combination of developmental screening and comprehensive evaluation. Routine developmental screening at well-child visits uses standardized tools to identify children who may warrant further evaluation. In New Jersey, developmental concerns identified through screening can trigger a referral to the early intervention system, which conducts multidisciplinary evaluations at no cost to families.

A comprehensive evaluation assesses the child across all relevant developmental domains and includes observation, structured assessment tasks, caregiver interviews, and review of medical and developmental history. Depending on findings, specialists such as developmental pediatricians, neurologists, geneticists, or audiologists may be involved.

Why Early Intervention Matters

The earliest years of life are the period of greatest brain plasticity, the brain's capacity to form new connections and reorganize in response to experience. This makes the birth-to-three window uniquely powerful for intervention. As Cleveland Clinic notes, research has shown that early intervention services for children up to age three can minimize and often prevent the long-term effects of developmental delays.

Early intervention does not just accelerate skill development. It shapes the foundational neural architecture that everything else is built on. The communication pathways, self-regulation capacities, and social connection skills that develop in the first three years have lifelong consequences. Investing in them early is among the most effective things that can be done for a child's long-term wellbeing.

Treatment and Support Options for Developmental Delays

Treatment is individualized based on the specific areas and severity of delay. Common interventions include:

• Speech-language therapy: For delays in communication, language comprehension, or speech sound development. Learn more on our speech therapy page

• Physical therapy: For delays in gross motor development, walking, balance, or coordination. Learn more on our physical therapy page

• Occupational therapy: For delays in fine motor development, sensory processing, self-care, or adaptive skills. Learn more on our occupational therapy page

• Developmental intervention: Broad support across cognitive, social, and developmental domains, provided by child development specialists

• Social work support: Helping families navigate the service system, understand their rights, and access resources. Learn more about our social work services

For children under three, all of these services may be available through New Jersey's early intervention program, which provides services in natural environments, typically the home, at no or reduced cost based on family income.

When Should Parents Seek Help?

Do not wait for a missed milestone to become a pattern before acting. If your child is not meeting milestones within typical ranges, or if your instincts tell you something is different, seek an evaluation. Early evaluation does not commit a family to long-term services. It provides information, and information is the foundation of good decision-making for a child's development.

In New Jersey, any parent can refer their child to the early intervention program for evaluation. No physician referral is required, and the evaluation is free. Visit our FAQ page for more about what to expect from the early intervention evaluation and service process.

How Innovative Interventions NJ Can Help

At Innovative Interventions, our multidisciplinary team provides speech-language therapy, physical therapy, occupational therapy, developmental intervention, and social work services for children birth to age three throughout New Jersey. All services are provided in the child's natural environment: typically the family's home, the setting where young children learn best.

We take a family-centered approach, which means that caregivers are not just observers. They are active participants in every session, learning the strategies that carry their child's development forward between visits. We serve families across Bergen County, Hudson County, Essex County, and surrounding areas in New Jersey.

If you have concerns about your child's development, contact Innovative Interventions today to request an evaluation or learn more about early intervention services in your area.

Frequently Asked Questions

Can a developmental delay resolve on its own?

Some mild delays do resolve with time, particularly when environmental factors are addressed. However, waiting without intervention risks missing the most effective window for support. Early evaluation provides clarity about whether watchful waiting or active intervention is more appropriate.

Is global developmental delay the same as intellectual disability?

Not necessarily. GDD is a descriptive diagnosis used when a child under five shows significant delays across multiple domains. Whether those delays reflect an underlying intellectual disability is usually determined through more comprehensive cognitive testing, which may not be reliable in very young children.

How do I access early intervention services in New Jersey?

You can self-refer your child to the New Jersey Early Intervention System (NJEIS) by contacting your county's early intervention program or by reaching out directly to an early intervention provider like Innovative Interventions. No doctor's referral is needed.

What is the difference between a speech delay and a developmental delay?

A speech delay affects only communication development. A developmental delay is broader and may involve speech alongside motor, cognitive, or social-emotional development. When delays span multiple areas, the term global developmental delay may be used.

Can a child with developmental delays go to a regular preschool?

Many children with developmental delays attend general education preschool, sometimes with support through an IEP or additional services. The appropriate setting depends on the child's individual profile and the resources available in the specific program.