Not too much you can do for the moment.
Mine's the same, showed up on the 20 week scan as covering my cervix. Sonographer seemed supremely unconcerned and I am being rescanned at 36 weeks to see if it's moved.
Since then, of course, I have scared myself half to death by googling. But, to be honest, other than be alert to bleeding etc, there's not really anything you can do.
How many weeks are you now?