I had it with DS but it hit me at around 24wks - lots of injections, Nefedipine tablets and bed rest got me through to 36.6wks when I ended up being induced. It was a very nervous and uncomfortable time...I feel for you! A girlfriend also had it with her first pregnancy, and again with her second, hit her around the 28wk mark, she ended up having her second at just under 38wks because of it.

Rest as much as possible, good luck