In brief
- Prechtl's General Movements Assessment (GMA) is a non-invasive, observational tool that evaluates the quality of an infant's spontaneous movements to predict neurodevelopmental outcomes, particularly cerebral palsy.
- It requires only a short video recording of the infant lying awake on their back. No special equipment, no needles, no handling by a clinician.
- Absent fidgety movements are the single strongest early predictor of cerebral palsy, with sensitivity around 94 to 98 percent in the published literature.
- The GMA works in two developmental windows: the writhing period (birth to about 6 weeks post-term) and the fidgety movement period (about 8 to 20 weeks corrected age).
- It is recommended in international clinical guidelines for early CP detection and is far more accurate than waiting for a diagnosis at 12 to 24 months.
If your baby was born premature or had a difficult birth, and you have been told to wait and see whether motor problems develop, the General Movements Assessment is a test you should know about. It is the earliest reliable predictor of cerebral palsy that currently exists, it is non-invasive, and it can be done from a short home video.
What is the General Movements Assessment?
The General Movements Assessment (GMA) was developed by developmental neurologist Heinz Prechtl and colleagues at the University of Groningen in the Netherlands, building on decades of research into spontaneous movement in infants. It was first described in a landmark 1997 paper in Early Human Development and has been refined and validated extensively since.
The GMA does not test what a baby can do when coaxed. Instead it evaluates what the baby does spontaneously, on their own, when they are awake and settled. The idea is that the quality of spontaneous movement reflects the functional integrity of the infant's nervous system, and that characteristic patterns of abnormal movement predict later neurological problems with high accuracy.
How it works
The assessment is performed from a short video recording, typically 3 to 5 minutes, taken while the infant lies on their back wearing only a diaper. The infant should be in a state of active wakefulness, not crying or fussing. The video can be recorded at home by the parent and reviewed later by a trained rater.
The GMA evaluates two distinct developmental periods:
The writhing period (birth to roughly 6 weeks post-term)
During this period, the infant's spontaneous movements are writhing in character. The rater assesses their complexity, fluency, and variability. A normal writhing movement looks smooth and variable. Two abnormal patterns are recognised: poor repertoire (monotonous, repetitive movements) and cramped-synchronized (stiff, rigid movements where all limbs contract and relax at the same time). Cramped-synchronized movements during the writhing period carry the highest specificity for later cerebral palsy, meaning they are rarely found in infants who develop typically.
The fidgety period (roughly 8 to 20 weeks corrected age)
At around 8 weeks corrected age, writhing movements are gradually replaced by a new class of movement called fidgety movements. These are small, moderate-speed movements of the neck, trunk, and limbs that appear in continuous flow and change direction constantly. Think of them as a constant stream of tiny, gentle wiggles. The presence of normal fidgety movements at this age is strongly associated with normal neurological development. Absent fidgety movements are the single most powerful early predictor of cerebral palsy, with published sensitivity around 94 to 98 percent.
How accurate is it?
A large 2017 systematic review and clinical guideline by Novak and colleagues, published in JAMA Pediatrics, examined the predictive validity of early movement assessments for cerebral palsy and found that the Prechtl GMA during the fidgety period had the strongest predictive validity of all early infant assessments studied. Key figures from that review:
- Absent fidgety movements: sensitivity around 98 percent for later cerebral palsy.
- Term-age MRI: sensitivity around 86 to 89 percent.
- Hammersmith Infant Neurological Examination: sensitivity around 90 percent.
What the numbers mean
Sensitivity tells you how often the test correctly identifies a child who will develop CP. Specificity tells you how often it correctly rules out CP in a child who will not develop it. A test with 98 percent sensitivity will miss about 2 children out of every 100 who actually have CP. That is not perfect, but it is far better than waiting until a child misses a walking milestone at 18 months. It is also important to know that these figures come from research settings with trained raters. Results in routine clinical practice may vary.
How it fits with other early assessments
The GMA is not the only tool used for early CP detection, and it is most accurate when used as part of a broader assessment pathway. International guidance, set out in the 2017 clinical practice guideline published in JAMA Pediatrics, recommends combining the GMA with the Hammersmith Infant Neurological Examination (HINE) and term-age MRI, repeated over time, for the highest accuracy. Used together, these three assessments are more reliable than any one of them alone.
This approach, known as the integrated early detection pathway, gives families the earliest possible window for intervention during the period when the brain is most adaptable. An early detection finding is not a verdict. It is a head start.
What this means for you
If your baby was born early, or had a known risk factor for developmental differences (hypoxic-ischemic encephalopathy, a brain bleed, a genetic syndrome), the GMA is something you can ask about now rather than waiting. It does not require special equipment or a clinic visit. A trained provider can guide you through recording a short video at home and score it remotely.
The key point is that the window for the fidgety period is limited. It runs approximately from 8 to 20 weeks corrected age. After that, fidgety movements disappear naturally as voluntary motor control emerges, and the opportunity to assess them is gone. If your baby is approaching or past that window, other assessments such as the HINE or MRI are still available.
Ask your pediatrician or neonatal follow-up clinic whether they have access to a GMA-trained rater. In Idaho, not every provider is familiar with the assessment, but the training is becoming more widely available and parents are increasingly requesting it. You can also look into telehealth options with providers who offer remote GMA scoring.
This service is mentioned on our premature babies and NICU graduates page, which covers how CP can now be detected before 6 months and how DMI fits into early intervention.
What the GMA does not tell you
The GMA is a screening and prediction tool. It does not diagnose cerebral palsy. A finding of absent fidgety movements tells you the infant is at high risk and should be referred for intervention. It does not tell you the severity or type of CP that may develop, or whether the child's cognitive development will be affected. Those questions require ongoing follow-up and a full diagnostic assessment by a developmental pediatrician or pediatric neurologist.
The GMA also does not rule out all developmental problems. A normal GMA is reassuring but does not guarantee that no motor, cognitive, or behavioural differences will emerge later. It is one piece of information, placed alongside the rest of the picture.
Where to find training and assessment
The General Movements Trust, based in Graz, Austria, maintains a register of certified GMA raters and offers training courses internationally. The American Academy of Cerebral Palsy and Developmental Medicine (AACPDM) and the American Physical Therapy Association have recognised the GMA in clinical guidance. As awareness grows, more Idaho providers are becoming familiar with the assessment.
The Idaho Infant Toddler Program can evaluate any child under three at no cost, regardless of income, and can be a starting point for requesting a GMA. If the program does not offer it directly, they can refer to a provider who does.
Sources
- Prechtl HFR. State of the art of a new functional assessment of the young nervous system. An early predictor of cerebral palsy. Early Human Development, 1997;50(1):1-11. — PubMed
- Novak I, Morgan C, Adde L, et al. Early, accurate diagnosis and early intervention in cerebral palsy: advances in diagnosis and treatment. JAMA Pediatrics, 2017;171(9):897-907. — PubMed
Nothing here is medical advice, and no single assessment should change your child's care on its own. Discuss anything you read here with your child's pediatrician or therapist.