<P> The proportions of the female hip bone may affect the ease of passage of the baby during childbirth . Pelvimetry is the assessment of the female pelvis in relation to the birth of a baby in order to detect an increased risk for obstructed labor . </P> <P> Fractures of the hip bone are termed pelvic fractures, and should not be confused with hip fractures, which are actually femoral fractures that occur in the proximal end of the femur . </P> <P> The hip bone first appears in fishes, where it consists of a simple, usually triangular bone, to which the pelvic fin articulates . The hip bones on each side usually connect with each other at the forward end, and are even solidly fused in lungfishes and sharks, but they never attach to the vertebral column . </P> <P> In the early tetrapods, this early hip bone evolved to become the ischium and pubis, while the ilium formed as a new structure, initially somewhat rod - like in form, but soon adding a larger bony blade . The acetabulum is already present at the point where the three bones meet . In these early forms, the connection with the vertebral column is not complete, with a small pair of ribs connecting the two structures; nonetheless the pelvis already forms the complete ring found in most subsequent forms . </P>

Anatomical features of the coxal (hip) bone