It is common for parents to observe their newborn’s legs shaking, which can naturally cause worry. While unsettling, these movements are often a normal, temporary part of early development that most newborns outgrow without lasting issues.
Typical Reasons for Shaking
A primary reason for a newborn’s legs to shake is the immaturity of their nervous system. The communication pathways between the brain and the rest of the body are still developing, which can lead to involuntary and twitchy movements. As the nervous system matures, usually within the first few months, these movements become more coordinated and fluid.
Developing motor control also contributes to these movements. Different body parts may twitch at various developmental stages as the baby prepares for future milestones, such as lifting their head. For instance, fine tremors in the head or limbs during the first month of life can be part of this natural learning process.
Reflexes common in newborns can also cause leg shaking. The Moro reflex, or startle reflex, is an involuntary response to sudden stimuli like a loud noise or sensation of falling. It involves the baby extending arms and legs before bringing them back, usually fading by 4 to 6 months. Benign neonatal sleep myoclonus involves rhythmic jerking movements only during sleep, ceasing when the baby awakens. These harmless movements typically disappear by three months.
Signs to Watch For
While many instances of leg shaking are benign, certain characteristics may suggest a more serious underlying issue warranting medical attention. Tremors that are prolonged, lasting several minutes or longer, are a cause for concern. Shaking that is rhythmic and cannot be stopped by gently holding or repositioning the limb requires further evaluation.
Movements affecting only one side of the body, or asymmetrical shaking, can indicate a concern. If the shaking is accompanied by other concerning symptoms, such as changes in breathing, consciousness, extreme paleness, or a bluish tint to the skin, immediate medical consultation is needed. Other red flags include lethargy, poor feeding, or general unwellness.
Unlike benign tremors, seizures in newborns are caused by abnormal electrical activity in the brain. These seizures can manifest subtly, with signs like unusual eye movements, lip smacking, or bicycling leg movements, sometimes mistaken for normal newborn behaviors. Seizure activity often persists despite attempts to comfort or reposition the baby and may be associated with changes in vital signs. Differentiating between typical infant movements and potential neurological problems is important, though true seizures are less common.
Guidance for Parents
When observing normal leg shaking, parents can often soothe their baby by gently holding the affected limb or repositioning them. Swaddling can reduce the impact of the startle reflex and promote security. Maintaining a calm and quiet environment can prevent triggering reflexes that lead to shaking.
If there are any doubts or concerns about the nature of the shaking, always contact a pediatrician. Recording a video of the movements can be helpful to show the doctor, providing valuable information for diagnosis. The pediatrician can assess the baby’s health and provide reassurance or recommend further evaluation if necessary. Seeking medical advice is important for any unusual or persistent movements, even if they appear benign, to ensure the baby’s well-being.