|As a newborn and young infant, most of your baby's development and physical reactions will be determined by primitive reflexes. For example, if you brush your newborn's cheek, he will likely turns his head (rooting reflex), which helps him to find a breast or bottle for a feeding. Or if you place a nipple in his mouth , as it touches the roof of his mouth, it will cause him to begin sucking (sucking reflex).
There are many of other types of reflexes, most of which are present at birth, including the moro or startle reflex, walking or stepping, tonic neck reflex and the palmar and plantar grasp.
It is not always easy to demonstrate these reflexes and not all babies do them all of the time, so don't be surprised if you or your Pediatrician can't trigger all of the reflexes. More important, is your baby's overall growth and development. Absent, asymmetric or persistent reflexes might be a sign of a neurological problem, though, and need further evaluation.
Also called the startle reflex, the moro is usually triggered if your baby is startled by a loud noise or if his head falls backward or quickly changes position. Your baby's response to the moro will include spreading his arms and legs out widely and extending his neck. He will then quickly bring his arms back together and cry. The moro reflex is usually present at birth and disappears by 3-6 months.
This reflex is shown by placing your finger or an object into your baby's open palm, which will cause a reflex grasp or grip. If you try to pull away, the grip will get even stronger. In addition to the palmar grasp, there is also a plantar grasp, which is elicited by stroking the bottom of his foot, which will cause it to flex and his toes to curl. The palmar and plantar grasp usually disappear by 5-6 months and 9-12 months respectively.
Most parents are surprised by this reflex. If you hold your baby under his arms, support his head, and allow his feet to touch a flat surface, he will appear to take steps and walk. This reflex usually disappears by 2-3 months, until it reappears as he learns to walk at around 10-15 months.
Positive Support Reflex
Like the stepping reflex, if you hold your baby under his arms, support his head, and allow his feet to bounce on a flat surface, he will extend (straighten) his legs for about 20-30 seconds to support himself, before he flexes his legs again and goes to a sitting position. This reflex usually disappears by 2-4 months, until it becomes a more mature reflex in which there is a sustained extension of the legs and support of his body by about 6 months.
Tonic Neck Reflex
A postural reaction, the asymmetric tonic neck reflex, or fencer response, is present at birth. To elicit this reflex, while your baby is lying on his back, turn his head to one side, which should cause the arm and leg on the side that he is looking toward to extend or straighten, while his other arm and leg will flex. This reflex usually disappears by 4-9 months.
If your baby is on his stomach and you stroke neck to the spinal cord (paravertebral area) on his middle to lower back, it will cause his back to curve towards the side that you are stroking. This reflex is present at birth and disappears by 3-6 months.
Infants also have reflexive postural reactions that usually begin later in the first year of life. These postural reactions include:
This reaction usually appears by 4-5 months, and involves your infant's body turning to follow the direction of his head when it turns, helping him learn to roll over.
This is a protective response that protects your infant if he falls. Beginning at about 5-6 months, if an infant falls, he will extend his arms to try and 'catch' himself.
Beginning at different ages, the propping responses help your child learn to sit. The first is the anterior propping response, which begins at 4-5 months, and involves your infant extending his arms when he is held in a sitting position, allowing him to assume a tripod position. Next, lateral propping, appearing at 6-7 months, causes him to extend his arm to the side if he is tilted. Lastly, posterior propping, causing him to extend his arms backwards if he is titled backward.
In addition to looking to see if a reflex is present, the early visits to your Pediatrician will also help determine that the reflexes are going away when they are supposed to, since a persistence of a reflex might indicate a neurological problem.
It is also important that the reflexes are symmetric, meaning that they are the same on both sides of the body. An asymmetric moro reflex, for example, might mean that your baby has weakness on one side of his body.