Effect of modern obstetrics on mothers from Third-World countries

Mothers born and raised in third-world countries compared to women born in the United States are on average of shorter size, have less weight, have narrower pelvic dimensions, and give birth to smaller infants without much difficulty. This may be due to a low-protein diet and inadequate prenatal care. Those mothers who were born and raised outside the United States (therefore with narrow pelvic dimensions), but who eat a high-protein diet and receive adequate prenatal care after migrating as adults to the United States, give birth to relatively large infants. This results in a marked cephalopelvic disproportion and severe dystocia, which frequently leads to cesarean birth. It appears that nutritional factors during pregnancy and infancy play a role as important as genetic factors in the etiology of cephalopelvic disproportion.