Birth Injury Answers

Parent guide

When Your Baby Uses One Side More: What Parents Should Know

The short answer

Babies do not move in exactly the same way every time. But a repeated pattern of using one side more than the other is worth telling your baby's health care professional about. Examples include reaching with only one hand, keeping the other hand fisted, kicking one leg less, or crawling in a lopsided way.12

These signs do not prove that a baby has cerebral palsy, a stroke, or another condition. Children without cerebral palsy can show some of the same signs.1 The pattern is a reason to ask for an examination, not a diagnosis you should make at home.

Do not wait for the next routine visit if your baby has lost a skill, is suddenly moving one side less, or seems ill. Contact your baby's health care professional promptly for instructions.2

What parents often notice

A difference may be easiest to see during ordinary play, feeding, dressing, or floor time. You may notice that your baby:

NICHD lists using one side more during reaching, crawling, or moving among the early signs that should be discussed with a health care provider. It also lists reaching with one hand while the other stays in a fist after 6 months, and lopsided crawling after 10 months.1

One moment matters less than a pattern

A single reach is not a test. The useful questions are whether the difference happens repeatedly, whether it appears in more than one position, and whether it changes over time.

Try offering the same toy at the middle of your baby's body during calm, supervised play. Notice whether both hands come forward. Watch both legs during kicking and both sides during rolling. Do not hold down the side your baby uses more, force the other side to work, or turn this into a home exam.

Early hand preference can be a clue

Many adults describe a baby as right-handed or left-handed when one hand is used more. A strong hand preference in infancy can instead reflect difficulty using the other side. The AACPDM early detection pathway identifies abnormally early hand dominance as a reason to screen for cerebral palsy in babies 5 months and older.3

This does not mean every early preference is cerebral palsy. It means the clinician should look at the whole pattern rather than dismiss the difference as ordinary handedness.

What to record before the visit

A short, concrete record is more useful than trying to remember every movement. For three to seven days, write down:

A brief video can help show a movement that may not happen in the exam room. Record only during safe, supervised activity. Do not delay care in order to make a video.

What to ask at the appointment

Start with the observation rather than a diagnosis: "My baby reaches with the right hand, but the left hand usually stays closed. I have seen it every day this week."

Then ask:

The American Academy of Pediatrics says parent observations are an important part of evaluating a possible motor delay. Depending on the concern, a child may be referred for physical therapy, occupational therapy, or other assessment.2

What an evaluation may include

A clinician may ask about pregnancy, birth, the newborn period, feeding, hearing, vision, illness, and the timing of milestones. The examination may compare movement, posture, muscle tone, reflexes, and how both sides work during play.12

When cerebral palsy is a concern, the AACPDM pathway recommends standardized tools chosen for the baby's corrected age and risk history. These may include the General Movements Assessment for younger babies and the Hammersmith Infant Neurological Examination for older babies, together with brain imaging when appropriate.3

These are clinician assessments. A parent should not try to score them from an online video or checklist.

Why it is reasonable to ask now

The AACPDM pathway says parent concern is a valid reason to begin formal investigation and refer for early intervention. It also advises against a passive wait-and-see approach when clear clinical indicators are present.3

You do not need to know the cause before raising the concern. The next step is a careful examination and, when appropriate, standardized assessment and early support.

While you wait

Keep normal, safe floor play and routines unless your baby's care team has given different instructions. Place interesting objects where your baby can see them without forcing a movement. Let the clinician or therapist recommend activities that fit your baby's examination.

Do not buy a brace, splint, restraint, or therapy program based only on a social media video. Ask what goal an intervention addresses, how progress will be measured, and what evidence supports it for a child like yours.

Scope of this page

This page is general information. It is not medical advice and it is not legal advice. It cannot tell why a baby uses one side more or whether the pattern is normal. If your baby has lost a skill, is suddenly moving one side less, or seems ill, contact a health care professional promptly. If you believe your baby is having a medical emergency, call 911.

Editorial note: Sources were checked October 25, 2026. Medical review is pending. No attorney or law firm reviewed or sponsored this page.

Where these facts come from

1 Eunice Kennedy Shriver National Institute of Child Health and Human Development. What Are the Early Signs of Cerebral Palsy? 2021. https://www.nichd.nih.gov/health/topics/cerebral-palsy/conditioninfo/signs Link checked October 25, 2026.

2 American Academy of Pediatrics. Is Your Baby's Physical Development on Track? 2023. https://www.healthychildren.org/English/ages-stages/baby/Pages/Is-Your-Babys-Physical-Development-on-Track.aspx Link checked October 25, 2026.

3 American Academy for Cerebral Palsy and Developmental Medicine. Care Pathway for Early Detection of Cerebral Palsy. 2020. https://www.aacpdm.org/publications/care-pathways/early-detection-of-cerebral-palsy Link checked October 25, 2026.