The other issue can be that with our modern high carb high sugar diet, babies can get disproportionately large; this is why doctors always check for gestational diabetes, which can cause this. As type 2 diabetes is rising rapidly, no doubt gestational diabetes is too. It also predisposed a woman to type 2 diabetes later in life.
Generally though, when they say things like "hips too narrow", it's generally not true for healthy woman, just an excuse for justifying a C-section for "failure to progress", which is not a valid reason, but a common one.
