Are You Wondering What Should a Baby Wear Under a Swaddle?

Overheating a baby is a serious risk, so parents need to consider what a baby should wear under a swaddle carefully. Too many layers might cause your baby to overheat; babies cannot properly regulate their body temperature as an infant.

The older generation believed that babies needed multiple layers of clothing. When I had my first child, my mother put socks under her sleepers and a onesie, but then she would sweat! 

Nowadays, parents know that overheating a baby dramatically increases the risk of SIDS. So, if you’re wondering what you need to put on your baby under a swaddle, let’s take a look at what the experts recommend.

Can Your Baby Get Too Hot in a Swaddle?

Yes! Babies get too hot in a swaddle when they have too many layers underneath. Here is what the American Academy of Pediatrics has to say about this topic.

In general, infants should be dressed appropriately for the environment, with no greater than one layer more than an adult would wear to be comfortable in that environment… 

Overbundling and covering of the face and head should be avoided.

Swaddling keeps your baby warm during naps and nighttime, which is often a benefit because babies cannot regulate temperatures. However, in warmer environments or too many layers, swaddling might overheat your baby, leading to hyperthermia. 

The risk dramatically increases if you cover your baby’s head with a hat or cap. Similar to how covering our ears in the winter trap heat and keep us warmer, heat escapes through their heads, and keeping it uncovered allows your baby’s body to stay cool. 

Signs Your Baby is Overheating 

Parents must monitor their babies when swaddled to ensure they are safe and not overheating. Watch for signs of overheating. Here are some to note. 

  • Hot Skin
  • Sweating 
  • Rapid Breathing
  • Red Skin

Trust your instincts. If you believe your baby is too hot, it’s best to unswaddle and check your baby than to let them continue to sleep when they’re too hot and potentially to overheat. 

Do Babies Wear Anything Under the Swaddle?

Swaddle blanket for newborn

If you’re wondering – should newborns wear onesies under swaddle – the general rule of thumb is yes, your baby should wear one extra layer compared to you. If you feel comfortable in a t-shirt and sweatpants in your home, then all your baby needs is a onesie underneath the swaddle; long-sleeve onesies are acceptable. 

Let’s look at what your baby should wear during the seasons. 

What to Wear in the Summer Under the Swaddle

Summertime is the greatest risk of overheating in a swaddle. Make sure you dress your baby in light clothing that is meant for hot weather.

Remember that:

Babies do not need more than one layer of clothes in the summer. It’s possible to swaddle your baby when they only wear a diaper. This is safer in the summer than adding another layer.

If your house is cool due to air conditioning, consider putting a onesie on your baby made of 100% cotton and short-sleeved. Avoid using sleepers, long-sleeved onesies, or materials that are not breathable. 

Also, summer is a great time to use breathable swaddles. Muslin cotton is ideal because it allows for maximum airflow and reduces the risk of overheating. Stay away from synthetic fibers in the swaddle during the summer; synthetic fabrics trap heat and reduce breathability. 

What to Wear in the Winter Under the Swaddle

Keeping your house warm in the winter may be a problem, so swaddling ensures your baby isn’t too cold. Babies don’t sleep well when they’re cold – who blames them?

If your house is below 65℉ at night, your baby should swear a swaddle or a sleep sack (here are the differences between these two), along with a long sleeve sleeper. It’s best to use a swaddle with a higher rating than 1.5 TOG if your house is consistently cold. 

If your house is between 68-70℉ in the winter, a swaddle or a sleep sack along with a short sleeve onesie or a long-sleeve sleeper is sufficient. Avoid using materials rated higher than 2.5 TOG. 

What Else to Consider When Dressing Your Baby Under the Swaddle

A few additional factors aside from the season help you determine what a baby should wear under a swaddle. Here’s what you should consider.

Room Temperature

Keeping your house at the appropriate temperature for your baby is an essential part of knowing how to dress your baby. Parents need to monitor their baby’s room temperature; consider keeping a thermostat in their room to be sure. 

The ideal room temperature for infants is between 68-72℉. If the room still feels hot and humid, consider using a fan that oscillates around the keep. 

If your baby’s room is too hot, no matter what you try, it’s safest not to swaddle your baby. 

Material and Thickness of the Swaddle

When you look at swaddles, most have a TOG rating, which is the unit of measurement that indicates thermal insulation. Popular brands, such as HALO and SwaddleMe, include their TOG ratings in each sleep sack and swaddle description. 

Always look at the TOG rating when selecting a swaddle for your baby!

Here are the general recommendations based on TOG ratings and when to use them.

TOG RatingFabricsWhen to Use
0.5100% Cotton Muslin
100% Cotton
Coolest, ideal for warmer seasons and climates. This is an excellent TOG rating for the summer.
1100% Cotton
100% Cotton Muslin
Best for spring, summer, and fall, and moderate weather.
1.5100% Cotton Muslin
100% Cotton
Warmer, ideal for the fall or spring. The fabric typically has 2-3 layers but all breathable.
2.5MicrofleeceUse this rating for chilly seasons and climates, such as fall evenings when the temperatures dip lower.
3Microfleece – Winter WeightWarmest, ideal for winter. Using this when the temperatures are low outside and inside.

How Your Baby Looks & Feels 

Take a look at your baby and touch his body. Does his chest feel warm and comfortable? Is his forehead sweaty?

What your baby looks and feels like helps you determine if you’re dressing them wrong. If their hands or feet are cold, you might need to add another layer or use a sleeper covering their feet. With close monitoring and trial and error, you’ll find the perfect combination for your baby.

Final Thoughts

In most cases, babies should swear a onesie under a swaddle. During the winter, placing a long-sleeve onesie or a sleeper underneath of a sleeper is sufficient. In the summer, some babies only need to be swaddled in their diapers to avoid overheating. Be sure to watch your baby, use the appropriate materials based on season, and assess how they handle the combination of layers. 

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