my mchn (she is one of the good ones) told me that in the UK the sids advice says to sleep on back or side, not just back.

my dd slept on her side from the day she was born as she hated the back and kept choking on her own saliva - did it once to the extent that she stopped breathing so for her the back was much more dangerous.

the absolute biggest risk factors for sids are any exposure to cigarette smoke, dirty mattresses, bumpers adn things they can choke or suffocate on - as wel as soft, rather than firm mattresses. babies who have had any formula at all (even one bottle) are at a greater risk so if you are breastfeeding - keep at it.