mine was covering up until my 20 week scan. had to go on light duties at work and finish up at 30 weeks and was very careful but no one told me to be on bed rest I had another scan at 22 weeks, then 32 weeks then 36 weeks and it slowly kept moving until it was a MASSIVE 1cm away form the cervix which was just enough for me to deliver vaginally. they like it to be at least 2cm, I did have A LOT of bleeding post birth and was monitored a bit and had to have placenta delivered ASAP by cord traction and injection and then some syntocin to make uterus contract up quicker but having said that I was home the next arvo and just had my blood count monitored. I was very lucky I never got any bleeding through the whole pregnancy. Every case is different though. maybe get a second opinion? 16 weeks seems quite soon to be on strict bed rest but I am not a doctor. Maybe I was just very lucky?