Ali Weatherford
I love the word primitive. It can have a negative connotation, but for me, it just describes things that have been around for a REALLY LONG TIME. We have primitive instincts and developmental patterns that have persisted since the beginning of human existence. I love to think about that. It means that I still have things in common with my most distant relatives!
One of the most obvious and amazing ways to see this is with newborn reflexes. A normal healthy newborn will do some very strange-seeming things that are actually designed with a purpose. Primitive reflexes show up in a newborn, and then go away once that baby achieves some developmental milestones and doesn’t need them anymore.
These reflexes are automatic and are controlled by the oldest part of the brain, the brainstem. This is the part of the brain that connects the big round complex thinking part of the brain to the spinal cord and cerebellum. Our involuntary vital functions like consciousness, breathing, blood pressure, heart rate, sleep, and instinctive behaviors, are controlled by the brainstem. Some people call the brainstem the reptilian brain. It’s the part that we share in common with other animals. It’s very basic, very old, and very critical for survival.
What are the primitive reflexes for?
The combined function of these reflexes is survival. Many of the primitive reflexes help a baby with feeding, and others offer protection from falling or injury. Human babies are born with big highly developed brains but underdeveloped bodies.
This is different from most other mammals. Their offspring are born with highly developed bodies, but their brains are not as highly developed as ours. A baby deer can be walking and feeding itself within an hour of birth. They can start running shortly after! Our babies don’t have bodies that are coordinated enough or strong enough to do these things, so they have primitive reflexes that make certain things happen automatically.
What are the primitive reflexes?
- The Sucking Reflex: This reflex is important for helping a baby coordinate breathing and swallowing. You can see it in action when you put something into a baby’s mouth a certain way. The baby will automatically clamp down and start sucking, even if it’s not going to get them any milk! Babies tend to be soothed by sucking.
- The Rooting Reflex: This reflex helps a baby feed. You can see it when you lightly touch the side of the baby’s face on the cheek. They will turn their open mouth in that direction. This helps a baby initiate feedings as often as possible which is really important in the early days of life. For new parents, this one can be confusing! Maybe you just fed your baby and then your partner takes the baby for some snuggle time. If they accidentally touch the side of the baby’s face with a finger or a shirt in just the right way, she might start rooting as if looking for a nipple! It doesn’t necessarily mean she’s hungry again, it could just be that the touch triggered the reflex.
- The Snout Reflex: This reflex is also related to feeding. When you touch the baby’s top lip, this reflex makes their lips pucker.
- The Palmomental or Grasping Reflex: This reflex may be helpful for feeding because the baby will often grab for a nipple. It may also help a baby hold on when being carried so they can avoid falls. You can see this reflex by stroking a baby’s palm. They will usually grip immediately and hold on tight!
- The Glabellar Tap Reflex: This reflex is most likely present to protect the baby’s eyes. They initiate the reflex by tapping the baby’s head between the eyebrows. This makes the baby blink. An older child or adult would stop blinking after a few times, but a newborn will continue to blink.
- The Asymmetric Tonic Neck Reflex: This reflex may be helpful for birth. When performing this reflex, the baby’s head turns to one side and that same arm automatically straightens out while the opposite arm bends up at the elbow. It’s thought that this can help a baby maneuver through the birth canal in a better position. You can see this by turning a baby’s head to one side or the other while they’re lying down.
- The Moro Reflex: This is also sometimes called the Startle Reflex. The baby looks startled when exhibiting this reflex as their arms suddenly fling out widely, and they spread their fingers. Sometimes the baby will cry. The baby may feel like they are falling, and this is the instinctive reflex. You can see this if you pull a baby’s arms up while they are lying down, and then let go of the arms. This one might be useful for parents to know about, because it can sometimes disrupt sleep. You can avoid it by keeping your baby’s arms tucked in securely, or by holding the baby close. Swaddling is sometimes helpful in preventing wakeups because of the Moro Reflex. You can also hold your baby’s arms tucked close to their body when trying to put them down for sleep, then slowly let go after they are completely relaxed onto the mattress.
- The Babinski Reflex: This is a reflex triggered by stimulating the bottom of the baby’s foot. The big toe will flex upwards and the other toes will spread out. It’s thought that this reflex helps a baby prepare for walking, and also with avoiding falls.
- The Stepping Reflex: This reflex might be the most surprising because it seems like a newborn is just too young for this! You can see this by holding the baby upright and setting their feet onto a surface. They can’t hold their weight up, but when they feel their feet on the “ground”, they’ll put one foot in front of the other as if they’re trying to walk! This reflex disappears at about 2 months, but will come back again when the baby is getting developmentally ready to walk (usually at the end of the first year). It’s thought that this reflex is helpful for feeding. A baby can use this reflex to push and scoot toward a breast for feeding when they are lying belly down on their mother’s body. This is part of a process called “The Breast Crawl” or “Self-Attachment”.
Why do these matter?
It’s true that knowing about many of these reflexes might not matter very much for a new parent. It can be fun to understand these things when you see them, but it might not affect the way you take care of your baby on a daily basis. It might be good to know about some of these reflexes as they relate to getting a good start with breastfeeding. You can take a class with us to learn more! These reflexes do, however, matter a lot to your baby’s care providers. A pediatrician or midwife will look for these reflexes in your newborn because seeing them in action is a way to know that your baby is healthy.
When a reflex is missing, it could be an early sign that the baby has some kind of developmental problem or health condition that needs to be addressed. For example, if the Moro Reflex is absent, it could indicate some kind of central nervous system dysfunction caused by a spinal cord injury or a condition like spina bifida or a tumor. So, these reflexes are a great way to track your baby’s early health and development. It’s also interesting to know that these reflexes disappear at slightly different rates, but that they should be all or mostly gone by about six months of age. If one of these reflexes continues much longer or comes back later in life, it’s usually an indication that something is wrong. Sometimes the primitive reflexes come back in adulthood if there is a brain injury, dementia, or a disorder like Parkinson’s disease.
Checking for these reflexes is a normal part of a baby’s first thorough physical exam which is usually done the next day after birth. It’s usually important and interesting for parents to be part of this exam, and when you know what they’re doing and looking for, it might even be fun!
Your own pediatrician or doctor will continue to look for these reflexes at the regular checkups over the next year. In the meantime, there isn’t much that parents need to do about these reflexes. They are automatic, and only needed for a little while. They go away on their own after a few months once babies are reaching certain milestones. If you’d like to keep track and watch, it might be helpful to let your pediatrician know if you suspect that any of the reflexes are persisting for longer than normal.
Resources
https://www.healthychildren.org/English/ages-stages/baby/Pages/newborn-reflexes.aspx
