Brachial plexus birth palsy (BPBP) is the most common peripheral nerve injury in children (prevalence <5.1 per 1000 live births) and conservative management is routinely used to manage them. We have previously systematically reviewed studies investigating primary conservative management, published between 1992 and 2002, and found these to be inconclusive. The aim of this review was to update our previous systematic review to include studies published between 2002 and 2008, synthesise the data thus obtained with that of our previous review and create an up-to-date body of evidence for conservative management of infants with BPBP.