There are studies that say breastfeeding mothers are very attuned to their infants and sleep in such a way as to protect them from being rolled over on.
Just make sure the bed is rendered safe. Don't let blankets flop over the baby since re-breathing the same air under a blanket could be very dangerous and make sure pillows and the edge of the bed are not going to pose a danger. Tie long hair back and make sure there are no strings/buttons that could be dangerous. AND don't co-sleep when under the influence of something that would make it difficult to wake.
We gave up the idea of putting baby to sleep in a separate bed the first week, he would not stay asleep for more than 15-20 minutes away from parental contact (whenever he cycled up into light sleep, if there wasn't a warm body touching him, he would wake up.) Now I can sometimes put him down in his crib for a nap but it rarely lasts more than 45 minutes tops.