The topic of co-sleeping has apparently been in the news recently. I can't find reference to the reports on our local NBC station .. nor can I find anything on the Today Show website (though lots of Colon Cancer links …
The Several studies have suggested over the years that co-sleeping may be implicated in fetal deaths. Some of the early Europeas studies, however, were pootly done, and it turned out that parents who smoked and/or drank alcohol were more likely to have kids die in the bed withe them. Other studies have clearly demonstrated that kids don't sleep as well when in the bed with parents. They are aroused more easily, and don't have as consistent or as deep sleep patterns as those who sleep alone.
… and these studies are then extrapoloated to suggest that co-sleeping is actiually protective agains SIDS. And in fact some studies support this contention .. whereas other studies do not.
For now … the REAL answer on whether this is a safe practice remains with the parents. trust them.