This was 2 years ago, so I'm assuming things are the same. DD turned breech at 37 weeks and came out with a dislocated hip.
She started wearing a harness when she was 1 day old. She wore it constantly for 6 weeks. Then for 6 more weeks, she just had to wear it at night. She sees a Pedi Orthopedic Dr and she had to have x-rays and ultrasounds until she was 1. Now, we have to take her in every 3 years (until she's 12) to have it monitored.
It really is heart breaking to see your child in it. The only clothes DD could wear over the harness were sleep sacks with the elastic bottoms.
Since DD was in a harness for basically, the first 3 months of her life, she couldn't move. Due to this, she didn't roll over until she was 7.5 months and we started her in an IE (early intervention) program to make sure she wasn't delayed in walking.
I was told this is genetic and any other childen I have could have this problem as well (more likely to happen if we have another girl). We had DS checked out when he was born and he does not have any hip problems.
Good luck to you and your DD. If the harness is something your DD has to wear, be prepared that she probably will be delayed in her milestones. Just remember that the earlier it is caught, the better and easier things will be later on.