I treat children with hip dysplasia as part of my job, and I know that there is no evidence that modern baby carriers cause this serious problem. In such cases they just need some help. It also allows you as a parent to provide security and closeness even when you cant offer 100 percent of your attention.
Positive for nursing, too, moms who carry their babies in a baby carrier also often say that they think it has had a positive impact on their nursing. Sometimes they should handle so many tasks in the same time, so they cannot deal with all of them.