Neonatal reflexes develop while the infant is still in the womb, and they are present at birth. They are natural instincts for the baby, not learned through experience. The reflexes are a predictable, automatic response of the nervous system to specific stimuli. Most of the neonatal reflexes typically disappear within a few months to a year due to maturation of the infant, but the absence of or variation in reflexes might be a sign of abnormal development. Some reflexes, like sucking, are essential for survival, while others are merely spontaneous movements that are part of a baby’s usual daily activities.
These inborn reflexes are responses of an infant’s developing nervous system. The nerve endings receive stimuli through the senses such as sight and touch. The impulses created by the stimuli travel through the central nervous system, which tells the muscles to make a specific action.
Most of the neonatal reflexes slowly disappear over the first year as an infant matures. The length of time that a reflex is present varies by child. If a baby does not exhibit the expected reflex behavior, it can sometimes indicate problems with development, and a doctor will usually do further testing to make a diagnosis. Some reflexes, like the sucking reflex, do not fully develop until 36 weeks of pregnancy, which is why many premature babies are born with weakened reflexes.
Several neonatal reflexes are part of a baby’s survival instincts, such as the rooting and sucking reflexes. These are necessary for a newborn to begin feeding. First, the rooting reflex occurs when a baby’s cheek or mouth is lightly stroked. A baby will turn his head and open his mouth in the direction of the stroking, helping him to search for a bottle or breast. Then, when the roof of the mouth is touched, a baby will begin to suck rhythmically, and it is coordinated with swallowing.
Other neonatal reflexes are muscle movements in reaction to a stimulus. For example, the grasp reflex happens when the palm of a baby’s hand is stroked, which will automatically make him clench his fist. Another example is the Moro reflex, also known as the startle reflex, which occurs when an infant is surprised by a stimulus like a loud noise or sudden movement. When startled, a baby will fling his arms and legs out symmetrically, followed by quickly drawing them back in to his body towards his chest.