The Cost of Feeding a Baby

I think one of the things that humans have done, and this is a kind of evolutionary biology catch all. It seems to me if the baby is allowed to demand so much nourishment before it's born, that it endangers the life of the mother. Now I would think because of the cost of that in the lives of the mothers that nature would have taken that into its economic appraisal of what it's worth. So somewhere along the line, the small proportion of poor outcomes seems to have been well overbalanced by how successful the rest of us are.