Parenting Insights
Babies are capable of some truly remarkable — and sometimes perplexing — behaviors. That adorable grin? It’s likely just gas. And when your little one wraps their tiny fingers around yours, it might feel like an instant bond, but it’s actually a reflex. So, if you catch your baby lying on their back, seemingly preparing to duel like a fencer, don’t rush to assume they’re destined for a future in swordplay (though imagine the scholarships!). The truth is, they’re simply exhibiting a reflex called the tonic neck reflex, which comes in two forms: asymmetrical and symmetrical. Let’s break down each one.
What is Asymmetrical Tonic Neck Reflex?
When most people mention the tonic neck reflex, they’re referring to the asymmetrical tonic neck reflex (ATNR), often dubbed the “fencing position.” This reflex occurs when a baby turns their head to one side; the arm on that side extends while the opposite arm bends at the elbow. Typically, this reflex is present until the baby is about five to seven months old. So, if your little one shows off their ATNR around Halloween, they might just make an adorable Robin Hood!
Why Does the Tonic Neck Reflex Occur?
One theory suggests that this reflex facilitates a smoother passage through the birth canal during delivery. Once the baby is born, ATNR can aid in finding their hands and enhancing hand-eye coordination. If you want to see this reflex in action, lay your baby on their back and gently turn their head to one side. If ATNR is triggered, the arm on the same side will reach out while the other arm appears to flex beside their head.
What is Symmetrical Tonic Neck Reflex?
In contrast, the symmetrical tonic neck reflex (STNR) typically emerges between six and nine months of age and assists babies in transitioning to a hands-and-knees position — hence its other name, the “crawling reflex.” STNR involves a baby bending their arms while extending their legs, and the reverse occurs when they move their chin away from their chest. This reflex is not only adorable to witness but also marks a significant developmental milestone, as it helps babies learn to coordinate their upper and lower body. However, STNR usually fades by nine to twelve months, coinciding with the baby’s walking skills.
In some instances, a baby may retain the STNR beyond their first year. If this occurs, don’t worry! Each child’s development follows its own timeline. You might observe your baby doing things like walking on their hands and feet (like a bear!), scooting while seated, or skipping the traditional crawling phase altogether. If you have concerns about your baby’s development, consulting with your pediatrician is the best course of action.
Other Newborn Reflexes to Be Aware Of
Several reflexes can help explain your baby’s movements:
- Moro Reflex: Causes the baby to startle, cry, and pull their limbs in.
- Rooting Reflex: An instinctive response where a baby turns their head when the corner of their mouth is touched, searching for a nipple.
- Grasp Reflex: Triggered by a light touch to the palm, causing the baby to grasp.
- Suck Reflex: Prepares the baby for nursing, starting around the 32nd week of pregnancy.
- Stepping Reflex: Makes it appear as though the baby is taking steps when held upright with their feet on a solid surface.
For more information on pregnancy and home insemination, check out this excellent resource from the NIH. Additionally, if you’re curious about other topics related to baby development, be sure to read more on our other blog post here.
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In summary, the tonic neck reflexes, both asymmetrical and symmetrical, play crucial roles in a baby’s development. These reflexes not only assist in physical coordination but also provide insight into the baby’s growth milestones. Always consult with your pediatrician if you have concerns about your baby’s development.