What are the potential causes of gross motor delay in a 9-month-old infant?

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Last updated: March 25, 2025View editorial policy

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From the Guidelines

If your 9-month-old is showing gross motor delay, consult your pediatrician promptly for evaluation, as early intervention is crucial for optimal development. At this age, most babies should be sitting without support, crawling or moving around in some way, and possibly pulling to stand, as noted in the American Academy of Pediatrics (AAP) policy statement 1. Delays might include not sitting independently, lack of crawling attempts, or inability to bear weight on legs.

Potential Causes of Gross Motor Delay

Some potential causes of gross motor delay in a 9-month-old infant include:

  • Muscle tone issues, such as hypotonia, which can affect gross motor skills development 1
  • Neurological factors, such as cardio-facio-cutaneous syndrome, which can cause delays in gross motor skills, including walking and language development 1
  • Individual developmental timing, as some children may develop at a slower pace than others
  • Other medical conditions, such as progressive neuromuscular disorders, which can manifest as a loss of previously attained gross or fine motor skills 1 Your doctor will assess your child's overall development and may refer you to a pediatric physical therapist for specialized evaluation and intervention.

Recommendations for Parents

To encourage movement and development, provide plenty of:

  • Tummy time and floor play opportunities
  • Create an environment that motivates your baby to reach for toys and practice new skills. Many children with early delays catch up completely with appropriate support, which is why early identification and intervention are so important for optimal development, as emphasized by the AAP 1.

From the Research

Potential Causes of Gross Motor Delay

The potential causes of gross motor delay in a 9-month-old infant can be attributed to various factors, including:

  • Hypotonia, which is a condition characterized by low muscle tone, as seen in the case of type 1 spinal muscular atrophy (SMA) 2
  • Neurodevelopmental disorders, such as Developmental Coordination Disorder (DCD) or Cerebral Palsy (CP) 3
  • Infantile idiopathic scoliosis, which can cause motor delay due to the abnormal curvature of the spine 4
  • Autism Spectrum Disorder (ASD), which can be predicted by early motor delays during the first year of life 5

Risk Factors and Assessment

Family physicians can evaluate for risk factors that may adversely affect motor development, including review of the medical and social history of the child and the parents or caregivers 6. After a gross motor delay is identified, the physician should determine the likely cause of the delay, identify any anatomic etiology, and assess for features that may require further evaluation, such as laboratory tests, imaging, or referral to a subspecialist 6.

Importance of Early Identification and Intervention

Early identification of gross motor delay and underlying causes can facilitate referral for early intervention services, which can enhance parent-child interaction, adaptive behavior, communication, and socialization 5. Accurate and timely referral to appropriate specialists may assist families in obtaining a diagnosis for their child and guide necessary interventions 2.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Physical Therapy for a Child With Infantile Idiopathic Scoliosis and Motor Delay.

Pediatric physical therapy : the official publication of the Section on Pediatrics of the American Physical Therapy Association, 2017

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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