According to the International Hip Dysplasia Institute, the most unhealthy position for the hips during infancy is when the legs are held in extension with the hips and knees straight and the legs brought together, which is the opposite of the fetal position. The risk to the hips is greater  when this unhealthy position is maintained for a long time. 
The healthiest position for the hips is for the hips to fall or spread naturally apart to the side, wit hthe thighs supported and the hips and knees bent.  Free movement of the hips without forcing them together promotes natural hip development.
The Medical Advisory Board of the IHDI does not endorse nor advise against any particular baby carrier or other equipment.  This document aims to provide information about healthy hip development to guide manufacturers in the development of safe design of infant equipment, and to help parents make informed choices about the devices they use for their babies.  i-Angel has been certified by a juried committee that judged various carriers with respect to the hip posture stability in accordance with the above International Hip Dysplasia Institute safety recommendations for parents and child carrier manufacturers.
  Thighs are NOT supported to the knee         The thigh is supported to the knee joint.
 joint.  Thus, the resulting force to the hip     The forces on the hip joint are minimal
  may cause hip dysplasia.                                   because the legs are supported and the
                                                                  hip is in a more stable position.