Overview of the Fencing Reflex in Newborns

newborn baby

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As you watch your newborn develop, it's important to know about all of the involuntary movements babies exhibit, including the fencing reflex. This motion causes babies to assume the "fencing position" when placed on their backs. Your baby may look like he is challenging an opponent "en garde" with an invisible foil. Learn more about why babies have this reflex.

Test It Out

To test the fencing reflex, place your baby on their back and turn their head to the right. The reflex occurs whereby the right arm extends straight, and the left arm (opposite side) will flex alongside the head, and vice-versa when the head is turned in the other direction.

This reflex should be present at birth. It’s thought that this reflex helps prevent a baby from rolling over onto his stomach before his brain and body are ready. This is another good reason why putting your baby on his back to sleep is important.

Other Names for the Fencing Reflex

The fencing reflex is also called Asymmetrical Tonic Neck Reflex; though your partner might think it’s very funny and call it Captain Morgan’s Reflex. 

Importance of the Fencing Reflex

This reflex is an important sign of your baby's nervous system development and function. If your baby never exhibits this reflex, talk to your healthcare provider at the next check-up. Sometimes a trained eye can help you spot this one a little better. If, on the other hand, your baby is in this position the majority of the time, contact your health care provider immediately as it could be a sign of a larger neurological disorder.

This involuntary movement will gradually disappear around 4 months of age. If it persists too long, it can hinder normal development of coordination.

Types of Newborn Reflexes

There are other involuntary motions vital to your little one's healthy development. Most reflexes will disappear between 3 months and 6 months of age. 

  • Palmar grasp: If you touch the palm of your baby's hand, his fingers will automatically curl around and cling to your finger. In other words, your newborn will "hold" your hand. It's also known as the Darwinian reflex. You can imagine how it is important it has been throughout human history for a baby to maintain a hold on his mother.
  • Moro reflex (or startle reflex): This reflex is why your little one reacts to a loud noise. He will involuntarily extend his arms, legs and fingers and arc
  • Sucking reflex: Your baby will automatically begin sucking if you touch the roof of his mouth with your finger, a pacifier or a nipple. 
  • Rooting reflex: This reflex helps your little one locate the breast or bottle to begin feeding. Try it: Stroke your newborn's cheek. He'll automatically open his mouth and turn his head toward the side that was stroked. 
  • Stepping reflex: Your newborn will look like he's "walking," placing one foot in front of the other when you place his feet on a flat surface.
2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Konicarova J, Bob P. Asymmetric tonic neck reflex and symptoms of attention deficit and hyperactivity disorder in children. Int J Neurosci. 2013;123(11):766-769. doi:10.3109/00207454.2013.801471

  2. Zafeiriou DI. Primitive reflexes and postural reactions in the neurodevelopmental examination. Pediatr Neurol. 2004;31(1):1-8. doi:10.1016/j.pediatrneurol.2004.01.012

Additional Reading

By Stephanie Brown
Stephanie Brown is a parenting writer with experience in the Head Start program and in NAEYC accredited child care centers.