I was on bed rest from about 20 weeks to 30 weeks 6 days when the babies were born. At first it was restricted activity/modified bed rest, then full bed rest (up to bathroom only). I was also in and out of the hospital for up to 5 days at a time, though. None of this was due to pre-term labor, which I didn't experience (actually my cervix measured 4.5 cm the day before I delivered...go figure), but due to extensive bleeding from a placenta previa. I finally had a placental abruption at just under 31 weeks and the guys were born. This is all pretty rare, and not something to be scared of. I think pre-term labor is much more common.