Shortened Cervix??

Cora
When I had my anatomy scan this week, it was discovered that my cervix is shortened, 2.4mm instead of the normal 3.5mm. I'm doing another transvaginal u/s in two weeks, but I've never had this with any other of my pregnancies. Has anyone had/has this? What kind of symptoms (aside from bleeding, discharge and contractions) should I be concerned about?