It has long ago been proven that putting a baby to sleep seperately from the mother increases the risk of SIDS. In fact, that is precisely why SIDS is called "cot-death" in the UK and "crib death" in the US and Canada.
MOst countries around the world of course cannot afford a separate room for a new baby. OR even a cot. This is a preserve of the rich world.
In Japan, where I live, all mothers sleep with their children until around age eight. Even if they do have enough space to make a separate bedroom for the child they choose to keep their children with them.
Not saying everyone has to do this, but I'm just pointing out how silly it is to be dogmatic about co-sleeping.
THe concept of putting a baby to sleep separately was aggressively pushed in the mid-twentieth century by so-called child "experts" who were invariably male. They also pushed formula onto mothers and all but destroyed breastfeeding.
Breastfeeding makes the chance of SIDS even less likely because the mother's sleep cycles are in synch with the baby. If she takes a sudden deep breath, the baby will too. THis happens even if a baby is NOT being breastfed. So co-sleeping stimulates a baby's breathing.
There are a couple of things you should look out for, though. In Japan, everyone sleeps on foutons on the floor and this is extremely safe, but if you have a big soft mattress then that could be a problem. Also, they say that alcohol can impair your awareness of the baby, but not sure if that's true. In Japan, it's common for the father not to sleep in the same bed as the mother-baby unit until the child is a bit older. I do think men should take a step back and allow a mother and baby the space to bond.
Having said that, co-sleeping is not for everyone. But I think it's cultural elitism to suggest that it is The Wrong Way To Do Things, though,