Hi, I have 2 questions I went to check on my 5 mth old baby during the nap and found them up against the side of the cot, sort of on their side/tummy but their right arm was completely down the side of the mattress (between the mattress and the side bars). Is this a sids risk? We have followed the guidelines on our cot for the mattress and never had this issue with our son, 4 years ago. I've measured around it and it just fits the safety standards for gaps between the mattress and sides. Should I be buying a slightly bigger custom mattress or a new cot? Are AirMesh cot wraps considered safe to use? We use the AirMesh brand Thanks!

Red Nose recommends that a mattress fits snuggly in the cot, with no more than a 20mmspace between sides of mattress & cot (when mattress is centred).
https://rednose.org.au/article/what-is-a-safe-cot
There can be a risk of entrapment in some instances if the mattress does not fit snuggly.

Red Nose recommendations are to “always place baby on back for sleep” not baby must always sleep on their back.
https://rednose.org.au/article/red-nose-safe-sleeping-recommendations

Most babies will be rolling over by 4- 5 months. Some earlier, some later.
This is very normal as babies grow & become stronger.
Many babies then prefer to sleep on their side or tummy.
This is not something that needs to be stopped. It is important to make the “new” environment as safe as possible.
https://rednose.org.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over  (please read full article)

Good to see you have stopped swaddling/wrapping & moved baby to their cot.
Babies need arms free & the space of a cot to roll well & safely.
Ensure mattress is firm & flat & nothing soft or loose in the cot.
Continue to always place your baby on back for sleep.

How does baby go with tummy time when awake?
Increasing tummy time when awake is important to build upper body strength to roll well (both ways)

“Are AirMesh cot wraps considered safe to use? We use the AirMesh brand?”
What are the reasons for wanting to use this product?
Red Nose has no specific information about the safety of this.
If you do use this product, ensure you follow the manufacturer’s instructions in relation to installation to reduce the risk of entrapment.

Let me know if you have further questions.
What State are you from?