New parents often observe their newborn’s legs shaking, which can be concerning. However, these movements are frequently a normal part of development and typically do not indicate a serious health issue. Understanding the differences between typical and concerning leg shakes can provide reassurance.
Understanding Common Leg Shakes
Newborns often exhibit leg shakes due to their still-developing neurological systems. Immature pathways transmit signals from the brain to muscles, leading to jerky or uncoordinated movements. This neurological immaturity means the baby’s body sends more electrical impulses than necessary, resulting in quivering or trembling. Most movements are harmless and decrease as the nervous system matures, typically resolving by three months of age.
Another frequent cause of leg shaking is the Moro reflex, also known as the startle reflex. This involuntary response occurs when a baby is startled by sudden noise, movement, or the sensation of falling. During the Moro reflex, the baby may suddenly extend arms and legs before pulling them back towards their body, sometimes accompanied by crying. This reflex is present at birth and usually diminishes by four to six months as the infant gains better head support and motor control.
Newborns may also shiver or tremble if cold, as their bodies are not yet efficient at regulating temperature. Checking the baby’s torso for warmth helps determine if this is the cause. Excitement or overstimulation from noise or bright lights can overwhelm a newborn’s developing brain, leading to trembling. Hunger can also trigger leg movements and crying, as a temporary drop in blood sugar can cause shakiness.
Signs That Warrant Concern
While many instances of newborn leg shaking are benign, certain characteristics and accompanying symptoms might indicate a more serious underlying issue requiring medical evaluation. One concerning sign is shaking that does not stop when the leg is gently held. If shaking continues despite gentle restraint, it could indicate a seizure rather than a normal tremor.
Shaking accompanied by changes in responsiveness or abnormal eye movements warrants immediate attention. This includes staring, eye-rolling, or unusual blinking. Movements that are prolonged, repetitive, or rhythmic, especially if on only one side of the body or involving stiffening, should be evaluated by a healthcare professional.
Other symptoms alongside leg shaking suggesting a need for medical consultation include fever, difficulty breathing, lethargy, poor feeding, unusual crying, or changes in skin color, such as a bluish tint. These combined signs may point to conditions like low blood sugar (hypoglycemia), which can manifest as shakiness, sweating, and difficulty feeding. Other potential causes include certain types of seizures, which can present with rhythmic jerking or stiffening movements, or, less commonly, drug withdrawal if the mother used certain substances during pregnancy.
What to Do When Legs Shake
When observing your newborn’s legs shaking, note the movement’s characteristics. Note its duration, frequency, and any accompanying symptoms. This information is useful for consulting a healthcare provider. Taking a video can also help your pediatrician assess the movements accurately.
For common, non-concerning leg shakes, comfort measures can help calm your baby. If cold is suspected, swaddling your baby in a warm blanket or holding them close provides warmth and comfort. Gentle touch and reassurance can soothe an overstimulated or fussy baby. If hunger seems to be the cause, offering a feeding quickly alleviates trembling.
Contact your pediatrician if leg shaking does not stop when gently held, is prolonged or repetitive, or is accompanied by other concerning symptoms like changes in responsiveness, abnormal eye movements, fever, difficulty breathing, or lethargy. Your pediatrician can provide a proper diagnosis and treatment plan if necessary, and offer further guidance on distinguishing normal newborn movements from those requiring medical intervention.