The biggest risk is over heating and particularly if in a restricted environment, eg a muslin in a sleeping bag as baby cannot escape it. swaddle blankets are slightly better but depends on what baby is wearing and temp of the house etc.
Sue Macdonald, education and research manager at the Royal College of Midwives, said the college advised parents to avoid swaddling in general.
“There are concerns about the growing use of swaddling because of the possibility of overheating the baby, and the increased risk of cot death,” she said.
www.babies.co.uk/sleeping/a/blankets-and-bedding/
The Foundation for the Study of Infant Deaths (FSID) advises caution against swaddling as recent research suggests it could be an emerging risk factor for cot death. The Royal College of Midwives also advises against swaddling for this reason, but also because of concerns over the proper development of babies' hips.
If you do want to swaddle your baby, talk to your midwife or health visitor first, and follow these basic guidelines:
•Use thin materials and don't cover your baby's head
•Wrap your baby so that their legs are free to move - they should be able to move them up and outwards without any restriction
Putting your baby down to sleep To reduce the risk of sudden infant death syndrome (sometimes called cot death) the FSID advise you to: • put baby down on his/her back to sleep, never on his/her front or side • keep the cot at the side of your bed for at least the first six months • make sure the room is not too hot (16-20° is ideal) • make sure the mattress is firm and flat – no waterbeds or bean bags • make sure baby is not overdressed, or covered with too much bedding • never swaddle (wrap up) your baby • ensure that the bedding is not able to cover baby’s head • make sure the room is a smoke free zone • never sleep with baby on a sofa or armchair
I know it seems harsh - I did at times co sleep with my youngest but working where I do you learn a lot!
Hope some of this helps and sorry it's a lot.