Not necessarily.
Usually, the startle reflex is a normal neurological reflex that exists after birth and disappears as the central nervous system matures, usually disappearing completely after 6 months of life. If the startle reflex appears or disappears at an abnormal time, it indicates a disease in the body. The abnormal startle reflex can be caused by a variety of reasons, cerebral palsy being only one of them, in addition to clavicle fractures and brachial plexus injuries.