Whilst bed-sharing isn't a problem for the child, it might be for the parents: how do you express your love for each other when baby's in the bed?
The answer from parents who bed-share is that they just have sex elsewhere and at other times.
Obviously if you bed-share for a long time it's different. At first, you accept the baby's presence in your bed because you expect the situation to return to normal, with baby in his bed and you alone in yours. If this doesn't happen, the perception changes and parents see themselves as victims. They must make a decision, which can lead to conflict. It's healthier to air your conflicts openly, rather than feeling second-best (this is most common in fathers who feel rejected).
It's easier to say "I don't want to, I don't think it's right" and to explain why, rather than send the baby back to his own bed.
If they accept having their baby in bed with them, parents have to use their imagination for sex in other places. They should also think about getting away together from time to time, leaving the little one with his or her grandparents for example.