DS was in our room in a co-sleeper until he was about 8 months old. After 3 months of age, he was frequently in bed with me nursing once I came to bed, though he would start the night off in the co-sleeper. He transitioned easily to a crib in his own room at 8 months, and he slept much better there then he had begun to as a bed-sharer. Everyone was happy, though he didn't STTN until he was about 2. My milk slowly dried up when I went back to work, so he has been weaned from the breast since about 9 months. He still gets one bottle a night, usually at about 6 am. He's up for the day between 7 and 7:30.
Anyways... I am pregnant and due in July. Just recently, DS has started waking up in the middle of the night crying and asking to come into the "big bed". I always allow him to, and he usually spends the rest of the night there. Sometimes if he's too squirmy I'll take him back to his own bed, but by that point he is calm and okay with the transition. I can't really identify any reason for the recent change. He's not clingy during the day, he isn't exhibiting any new behaviors, and he seems just as happy and independent as ever. He's also perfectly okay with napping by himself.
Right now, I'm just taking the approach that he has some new emotional need that co-sleeping is meeting. I'm fine with that. But I'm curious if anyone else has ever stopped co-sleeping, only to start up again months or years later. Anyone BTDT? How long did it last? Any ideas on what the sudden change might be about?