Rebecca is pregnant

Rebecca is pregnant. At their OB/Gyn appointment, when they are close to full term, their practitioner promises to do her best to help with vaginal birth but says that it is an evolutionary reality that the human pelvis is not suited for birthing big-brain babies. She reassures Rebecca that this is just nature's way—the obstetric dilemma. 

You have been asked to explain to the practitioner why her comment may be ill-advised and recently questioned by some scholars. Describe the features of the obstetrical dilemma argument and then discuss the alternative model (The alternate model has been labeled by Dunsworth "the Energetics of gestation and fetal growth (EGG) model" and the metabolic crossover hypothesis by Peter Ellison.) What are the elements of and evidence provided for the critique and how is the claim made that the energetics model provides a more suitable explanation than the biomechanical/bipedalism argument?