Chapter 2 – Innate Reflexes

At birth, a baby’s nervous system is not a blank slate. It has had nine months to develop during intrauterine life, following a model shaped by hundreds of thousands of years of evolution. Through the mother’s body, it has already come into contact with the environment it will need to adapt to. Certain connections in the nervous system enable the baby to perform involuntary movements that are essential for survival and adaptation. At the same time, they are signs of healthy development: these are innate reflexes (3).

The neonatologist checks for their presence during the baby’s first hours of life, while the pediatrician monitors them throughout the child’s growth. Over the months, these reflexes—regulated by the peripheral nervous system—gradually fade as the brain matures, making way for voluntary movements. The first action a newborn must perform at birth is, naturally, to breathe. Through the first cries, air enters and expands the lungs, activating autonomous respiration. From this moment, heart-lung circulation begins: the heart rate can reach 180 beats per minute. Several other reflexes must also be present at birth. The main ones can often be recognized by parents (4):

• Moro Reflex
  When a newborn is laid on a flat surface and gently lifted a few centimeters with one hand supporting the head and the other the shoulders, then suddenly released with a quick motion, the baby reacts to the sensation of falling by spreading their arms, as if trying to find a wider support to maintain balance.
• Sucking Reflex
  When the baby’s cheek is gently stroked, they turn their head, attempt to reach the finger, and open their mouth to suck. This reflex helps the baby orient themselves and find the mother’s nipple when brought to the breast.
• Rooting Reflex
  Also called the Search Reflex. This reflex is often assessed along with the sucking reflex, as both are functionally related to feeding. It helps the baby locate their food source, and the sucking reflex then allows ingestion of milk. Head-turning associated with this reflex is also seen in other reflexes such as head-righting and body-righting. If the reflex persists or is absent, it may signal dysfunction in the central nervous system or the sensory-motor system. The response is triggered by gently tapping the area near the lips, causing the head to turn toward the stimulus.
• Crawling Reflex
  When placed on their stomach, a newborn will tuck their legs under the body and begin to crawl forward. This reflex is usually observed within the first 30 minutes after birth when the baby is placed on the mother’s abdomen and gradually “climbs” toward the breast.
• Babinski Reflex
  This reflex is normally observed from birth and typically persists until about six months of age. It occurs when the sole of the foot is stroked, causing the baby to fan out their toes and then curl them back in. The Babinski reflex is a reliable test for dysfunctions in the pyramidal tract, an indicator of voluntary movement capacity. However, spontaneous or overly sensitive activation may indicate irritability and should be considered pathological.

• Palmo-Mental and Palmo-Mandibular Reflexes
  These reflexes are present at birth and trigger facial responses when the palms are stimulated. The palmo-mental reflex is observed when applying simultaneous pressure to both palms, which may cause one or more of the following: mouth opening, eye closing, neck flexion, or head tilting forward. The palmo-mandibular reflex occurs when lightly scratching both palms causes the lower jaw to open and close. These typically disappear around three months of age. Some experts believe the palmo-mental reflex is shared with certain animals, helping infants cling to their mothers while feeding.
• Palmar and Plantar Grasp Reflexes
  When a finger or object is placed in the baby’s open palm (from the pinky side), they will grasp it. A similar response occurs when pressing the sole of the foot near the base of the toes. After the third month, this reflex tends to disappear and is replaced by voluntary grasping.
• Stepping Reflex (Walking Reflex)
  When held upright under the arms with feet touching a flat surface, the newborn will start moving their legs alternately, mimicking walking. This doesn’t mean the baby can walk yet, but rather the nervous system is practicing the connections and muscle coordination needed for future walking.
• Tonic Neck Reflex
  When the baby is lying on a flat surface with arms and legs close to the body, gently turning their head to one side causes the arm and leg on that side to extend. This reflex likely evolved as a protective mechanism to prevent the baby from rolling over if the surface tilts.
• Blink Reflex
  The baby closes their eyes in response to a loud sound or bright light. This is a protective reflex that will accompany us throughout life.