This happened to a friend of mine, and she used thick cloth nappies to keep the hips open until the ultrasound. Wearing bub in a carrier with legs in the "frog" position is also good. The ultrasound seems to be the only way to really tell with hip dysplasia, and opinions seems to differ about the best time to do it...some say asap, but some paed told her 6 weeks is the earliest they can properly diagnose.

I would try not to stress too much at this stage, and just book in for the ultrasound when you feel up for it and see what they say.