Swaddling is Terrible, According to Science

swaddling and SIDS

The Journal of Pediatrics published a new study investigating the possible relationship between swaddling and SIDS (Sudden Infant Death Syndrome). The study concludes, “These analyses indicate that the current advice to avoid placing infants on their front or side to sleep may especially apply to infants who are swaddled.”

Is this news? Not really. Sleeping face down (aka prone) while swaddled has previously been linked to a significant increase in the incidence of SIDS. Which is why parents must immediately stop swaddling as soon as their baby shows signs of being able to flip from back to stomach. Even if their child’s sleep goes immediately to crap. Even if tears are involved.

But based on the media coverage you would think that the study proves that swaddling is only slightly less dangerous than putting your child to sleep in a box of glass surrounded by angry pitt vipers.

The Washington Post shares, “Risk of SIDS death … was still greater among swaddled babies, compared to those who were not swaddled.”

According to the New York Times, “Over all, swaddling increased the risk for SIDS by about one-third.”

One third?

Well hard pass on swaddling then.

Sure, swaddling helps newborns sleep better and longer. And previous scientific overviews on swaddling suggested that it was beneficial as long as baby’s hips were loose and the baby was on it’s back. But if it increases the risk of death by 33% nobody should ever swaddle their child. Ever.

News You Can Trust

Fundamentally this is an issue about how the news reports on studies. Because parents of young children don’t have the time to dig into study methodology so they rely on trusted news outlets to break it down for them. To provide them with key insights they can use to make informed parenting decisions. But sadly that rarely happens.

I would get a bit ranty about this. But I don’t have to. Because John Oliver did a bangup job. Plus he’s adorable (check out those dimples!).

This happens ALL. THE. TIME.

Take a reasonable and nuanced piece of research and turn it into clickbait. Yahoo News and Psychology Today are two of the worst perpetrators, but Time, CNN, Huffington Post, and the NYT also do this.

Welcome to the Internet people.

Does Swaddling Increase the Risk of SIDS by One-Third?

In a word, no.

Swaddling and sleeping face down or on the side (which is a notably precarious position) is a SIDS hazard. Unswaddled tummy sleep before your child is flipping independently is also a SIDS hazard, but swaddled tummy sleep is worse.

Digging Into the Swaddling SIDS Study

This study is a meta analysis which is useful because it summarizes, collectively, what existing research says on a given subject. This is a good thing to do, because when you combine the data across multiple studies, you get a bigger sample pool to draw conclusions from. This is especially important when looking at SIDS because most individual studies have a relatively small sample size. And SIDS is, clearly, something we want to understand better.

However there are a number of glaring issues with the data that make it unreasonable to draw sweeping conclusions from the study.

None of the studies give a precise definition of swaddling, which in some studies was described as “infant wrapped in a sheet or light blanket.” This could mean the child was indeed swaddled or was simply put down for sleep with loose blankets (a known SIDS hazard). Thus we can’t draw broad assumptions about swaddling because the infants in the study may not have actually been swaddled.

The prevalence of swaddling is inconsistent across the four studies (ranging from 35.7% to 9.2%) and the SIDS group was almost 60% more likely to be swaddled than the control group (to be clear, there are swaddled babies in both groups). You might see this and jump to the conclusion that swaddling most definitely causes SIDS but a more accurate interpretation is that this is evidence that study and control group are not homogeneous, a crucial issue when comparing two groups.

The issue of heterogeneity comes up again resulting in the most recent UK study being excluded from further analysis. If we look at the odds ratios of the three remaining we see 2 straddling the bar (the bar represents an OR = 1, meaning that swaddling has no effect) with 1 study with a much higher range of values for the odds ratio.

I can’t find this Fleming study but it’s based on data comes from the Chicago Infant Mortality Study which looked at SIDS and racial disparity and the data specifically looked at kids who were at much higher risk for SIDS: 90% were nonwhite, 50% had mothers who smoked while pregnant, 50% were sleeping on soft-bedding, and 80% had never been breastfed. This data doesn’t represent the average average, but instead reflects high-risk infants who were far more likely to succumb to SIDS due to issues related to race, maternal smoking, lack of breastfeeding, unsafe sleep space, etc. irregardless of swaddling. And it’s the data from this study that makes up the bulk of the pooled data in the meta analysis, so it’s entirely possible that the results presented have nothing to do with swaddling and everything to do with the high-risk profile of the babies studied.

The most interesting part of this study is comparing the infant’s sleep position looking at at supine (sleeping on back), side, and prone (sleeping on belly), which confirms what has been suggested by previous research, that tummy sleeping while swaddled is enormously risky.

But we can’t draw sweeping conclusions from this data because of:

  • The lack of heterogeneity between the groups.
  • Very little commonality among the studies which span 30 years and 3 continents.
  • The fact that we don’t know if these children were swaddled or simply put to sleep with loose blankets.
  • The bulk of the comparative data is drawn from infants with numerous high SIDS risk characteristics.

Additionally, when looking at the final sleep position (back, side, tummy) we have very small sample sets to work from. The authors draw the conclusions that for prone sleep while swaddled “the risk was 19-fold” from a scant 5 cases.

Similarly there are only 38 cases of SIDS for babies who are swaddled and back sleeping. This is an extremely small data set to draw broad conclusions like “swaddling kills” from. Especially given that previous studies suggesting that swaddling might in fact, reduce the incidence of SIDS.

Which is likely why the authors DON’T say that swaddling causes SIDS. They DO point out that older babies are more likely to flip and thus suggest that weaning off swaddling earlier than 4-6 months might be wise. And it’s notable that of the 38 infants placed on their back to sleep swaddled, 7 of those who were lost to SIDS had managed to flip onto their tummy during the night.

Bottom Line on Swaddling and SIDS

And that, realistically, is the bottom line from all this bruhaha. Never place your child on their tummy while swaddled. And as your child gets older and stronger, you need to keep an eye out to ensure that you wean them off swaddling before they figure out how to flip over. The minute you see your baby starting to push up onto their side or make other moves towards flipping, the swaddle must go. Even if your solid night sleep goes with it.

And if you see headlines popping up that seem overly alarming or contrary to common sense, chances are that the “new study says” something entirely different from what’s being reported.

(Source: PhD Comics)


  1. What’s your opinion on “transitional” swaddles like the zipadee? My son is three-ish months and as soon as he started rolling I put him in that instead of swaddling bc he liked sleeping on his tummy..

    • I loved the zipadee for my son! He started hating the swaddle around 3 months and would fall asleep without it, and then startle himself awake. For us, it was one of those rare baby products that actually works well! (That said, it didnt magically help my son transition from the swing to the crib or sleep all night but it did act as a great swaddle transtition.)

    • Parents report that they’re great and there are many fans of the Zipadee and Merlin sleep suit. Are they safe while sleeping face down? The real answer is – I don’t know. It’s not been studied (because they’re too new) so if you’re looking for, “Is there scientific evidence that it’s OK for my tummy sleeper to sleep with a zippy or merlin sleep suit?” the answer is – ask again later 😛

  2. Thank you for your thorough analysis! I hate when people take scientific fact and water it down a whole bunch to scare people for no reason at all. And thanks for using a Ph.D. comic. Just awesome.

  3. Thank you! We can count on you for reasoned, evidenced-based approaches to baby sleep.

  4. This kind of reporting is ridiculous and sadly common. It’s so frustrating. I see the trickle down to parents that don’t have the time to dig into the nitty gritty and it makes you feel like everything is unsafe and then people end up passed out on a couch with baby because they can’t sleep in the crib. Sigh.

    Otherwise a timely topic because I’ve been thinking about this of late with baby number 2, he’s 4.5 months and I’d love to ditch the swaddle but he rubs his face and wakes himself up and has a habit of scratching his head bloody from eczema. He’s still swaddled in the swing with a 5 point harness but I also would like to move him to the crib. We’ve had success sleeping in the crib for naps (before a hellish growth spurt/regression) but the swaddle concerns me. He hasn’t rolled on his tummy yet but during playtime he’s getting on his side and trying to get over. Does that mean once we move to the crib, he should not be swaddled? I’m guessing we’ll need to do something like a zipadee to at least keep his head safe from his determined little claws.

    • I would wean him off the swaddle BEFORE moving to the crib. If you’re worried about scratching, other parents have had luck sewing baby socks or some other item to the sleeves of jammies to keep the hands covered.

      • Thank you Alexis! Will do. He’s got about 15 bloody scratches on his head today because I’m a day late trimming and filing his nails. Little stinker has long arms and claws at his head whenever he stretches or is tired or just woke up.

  5. Great article! I so hate baby sleep articles where it seems unlikely that the author has ever actually met a real baby. I swaddles both kids and have such a love/hate relationship with it. My first was swaddled for 7 months. I thought it would never end! My new little guy is 13 weeks and flat out refused the swaddle last night. I decided to try out a Merlin suit we have and he slept just fine! Hallelujah! He is almost certainty my last baby so methinks I am maybe, just maybe, done with swaddling!!

    • Those merlin suits are not cheap but people SWEAR by them.

      • I know. $40! Not bad if it buys you some decent sleep but a lot to blow if it doesn’t. Luckily, my friend lent me one too so I have a backup. Not having a backup of something that could easily get pee soaked and leave me with a sleepless night gives me panic attacks.

  6. Also wondering about the zipadeezip, which we transitioned to for our 6-month old who had a hard time ditching the swaddle. Do you think it is safe? He is sleeping on his belly now in the zipadeezip.

    • I can’t really say one way or the other. Logically it seems like they should be just fine (same with the merlin) but there haven’t been any studies so all I can share is a gut check on it.

      • Hi! I have a merlin suit for my baby, and as I understood it, based on the website info, the merlin suit should NOT be used if the baby can roll over onto his/her tummy while IN the suit. It’s meant for back sleeping only. We used it and loved it as a swaddle transition, helped especially when our baby learned how to roll onto his tummy but didn’t know how to roll back! He would cry and cry for us to flip him back over. But when we put him in the merlin, he’s not strong enough to roll over onto his tummy in it, so it keeps him on his back overnight…yay! so he can sleep instead of rolling over and getting stuck and waking up.

        • Btw, we are now using zipadee zip which is nice, still gives him a cozy feeling. And based on what I read, it is safe for tummy sleeping since baby can roll back in it. But the merlin is not safe for tummy sleeping since baby is restricted from rolling back and is then stuck on tummy.

  7. Thank you for this thorough analysis. Do you have any thoughts on Harvey Karp’s assertion in The Happiest Baby on the Block that swaddling can prevent flipping onto the tummy? I was somewhat startled at this statement, as he doesn’t seem to cite any support and it is a dangerous supposition when considering what can happen if a baby flips over while swaddled. I know you’re a Karp fan (and generally, I am too) so I was curious as to your thoughts. Thanks!

    • I can’t remember which study this was in but yes, there have been indications that swaddled babies are LESS likely to flip. Not that swaddles PREVENT flipping (you can definitely flip over while swaddled) but it seems to hinder flipping. I don’t remember Karp saying that you CAN’T flip while swaddled? I mean regardless – you’re definitely correct, it’s absolutely possible TO flip swaddled.

      • Gotcha. Thanks. He definitely didn’t go so far to say that swaddled babies CAN’T flip, but he really stressed that it can prevent flipping. I’m all for swaddling and that notion does make sense, but I was a little concerned about relying on the assumption that it really would prevent flipping, without any support. At this point it’s all academic because my baby is almost a year, rolls freely, and is out of the swaddle, but I always trust your insight on these matters. Thanks for the reply — I feel honored 🙂

  8. I think this:

    “The lack of heterogeneity between the groups.”

    Is a typo.

  9. Ummmm… How did you get to be funny and smart? I mean, seriously. Your analysis of the study and the article are truly amazing. My eyes started crossing but I was really happy not to have to figure all this shit out myself! Especially since I have an eight week old baby, which means there’s not much behind my crossed eyeballs going on anyways. I wanted you to know that this is my second child and I swore by your blog for my first and did everything you said and it was amazing. And then I forgot absolutely everything and now I have to read it all again! Anyways, I just wanted to let you know that I think you’re a badass.

  10. I just have a question (sorry if obvious ) But, my 5 month old can barely roll over (grand total of 3 times) while I swaddled. She is completely unable to move swaddled. In a previous article of yours, it implies to look for signs of rolling when swaddled since it’s so much harder for them to roll bound. Is that not accurate?

    • It IS harder to roll swaddled. But when they start rolling UNswaddled you are on high alert for rolling swaddled. So it’s time to work on weaning off the swaddle because it’s just a matter of time now.

  11. I just wanted to say I love the comic at the end. My hubby is a researcher and this sounds about right.

  12. What about swaddling for naps, and not swaddling for night? My 4.5-month old has been night sleeping (through the night) for months unswaddled, but he recently has started waking a few times per night (I know, I know, I shouldn’t complain), and his naps are crap (30-40 mins). So I tried nap-swaddling today and he took a great nap!!! I can keep an eye on him during those naps, so I’m not worried about him flipping. But will that mess too much with his sleep habits? Will he wake more at night because he’s used to sleeping while swaddled? I don’t have enough days of personal data yet to determine the answer.

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