When Does the Startle Reflex in Newborns Stop?
Newborns are easily startled by the sights and sounds of the world outside the womb. Some are even surprised at the sound of their own cries. The normal response to the loud noise, and also sudden movements, is called the startle reflex, also known as the Moro reflex. Babies do stop the reflex, once they become older, gain more control of their bodies and are have more life experience.
What It Is
The startle reflex is one of several newborn reflexes that your baby exhibits in the first few months of life. It is an involuntary act that is triggered by loud noises, sudden movements and anything that can “startle” a baby. The startle reflex is an unmistakable but necessary newborn act. Pediatricians look for the reflex at the baby's earliest well-child check-ups as sign of a healthy newborn baby.
How It Looks
The U.S. National Library of Medicine describes the startle reflex as an act that occurs as suddenly as its trigger event. When the baby is startled, he may cry for a moment before tensing his body. He throws his arms into the air with his hands apart and splayed open. His legs spread apart in the same manner. Limbs pull back suddenly as your infant's eyes go wide and his mouth opens. He stops crying for a moment. The action ends as quickly as it begins. Your baby relaxes his entire body, but often commences with crying.
Why It Happens
According to the Children's Hospital of Wisconsin, the startle reflex is a sign that the baby's brain and nerves are operating as they should be. It also means that the nervous system is alert enough to respond to stimulation quickly and spontaneously. A lack of startle reflex, according to the NLM, suggests brain damage, nerve damage or breaks in the limbs. Once the newborn gains more control of his body, the startle reflex does not return.
When It Stops
The startle reflex is strictly a newborn act. It should begin to disappear at the age of 3 months, according to the NLM, and is completely gone by 6 months old, according to the Children's Hospital of Wisconsin. Babies who still have a startle reflex as they near a year of age should see a pediatrician.