Swaddling and the Moro Reflex

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Swaddling has been around for centuries and is practiced in many parts of the world. Despite this many parents struggle with the decision of whether or not to swaddle their newborn while sleeping in the supine position (on the back).

On the one hand it seems to simulate the womb. And baby must be most comfortable in a womb-like state, right? On the other hand, swaddles can be overly restrictive, difficult to keep in place, and cumbersome for middle-of-the-night diaper changes. So the question is:

to swaddle or not to swaddle?

Swaddling also comes in handy for limiting that pesky Moro reflex that seems to always keep baby awake!

What is the Moro Reflex?

The Moro reflex, a sensation of free-falling, is a primitive response that occurs in two phases:

  1. the sudden upward extension of the arms and legs, sometimes accompanied by a slight tremor,
  2. followed by recoiling of the limbs inward towards the body.

It is seen in all clinically healthy infants from birth up to anywhere from 12 to 20 weeks of age.

Although this reflex may seem like a nuisance when trying desperately to keep your new babe sleeping, it likely serves a key evolutionary function. Moro (the reflex’s namesake) claimed that this reflex is inherited from our distant relatives, primates and bats, which cling to their mothers for safety. Others argue that it serves as an internal alarm system to ensure baby responds to danger.

It could be a combination of the two. A sudden jolt to signal alarm followed by recoil to cling to safety. In line with this, the Moro reflex is actually inhibited by the palmer, or grasp, reflex. This suggests that if the infant is already clinging to its mother the startle response is not required. 

An interesting parallel is that the sucking reflex has been reported to increase the strength and duration of the grasping reflex. This then minimizes the intensity of the startle reflex – hello soothers!

One of the most sure-fire ways to elicit the Moro reflex is to simulate a sudden drop in baby’s head position. This is something that is all too easily accomplished by transferring baby from your arms to the desired sleeping surface, thereby waking them after all your dedicated efforts to get.baby.to.sleep.

Try placing baby down bum first and slowly lowering her head with as much support as possible.

Swaddle! It Helps!

Ok so the Moro reflex isn’t going anywhere in a hurry, so here enters the hallelujah moment of the swaddle. It has actually been scientifically demonstrated 

  • that swaddling reduces arousals in infants that have progressed to quiet sleep, 
  • that infants exhibit fewer startles during REM sleep when swaddled than when unswaddled, 
  • and that they returned to sleep more quickly when full arousal did occur, thus decreasing the arousal potential overall. 

Interestingly, infants who were swaddled also experienced longer bouts of REM sleep than unswaddled infants. This is likely due to the decreased duration of arousals and more rapid return to sleep. It is possible that this longer REM sleep duration could be an added benefit, due to the role of REM in learning and memory. Another win!     

So it seems that swaddling may be your best friend when helping your newborn sleep in the supine position. 

It is important to note that when swaddling, make sure to always allow hip flexion and abduction in order to prevent hip dysplasia. Have the swaddle snug on top but loose on the bottom. Also, you don’t want the swaddle to be too tight around the chest as this can increase the incidence of pneumonia. And, you don’t want a swaddle that your baby can break free from leaving loose blankets that could be a smothering risk.

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