1. What are the characteristics of pregnancy and giving birth to a boy? 1.1 Body shape changes During the process of pregnancy and giving birth to a boy, the mother’s body shape will change. Generally speaking, mothers who are pregnant with boys are taller and thinner. Because male fetuses require more nutrients and space during development, mothers also need more nutrients and energy to support the development of their fetuses. 1.2 Increased appetite. Mothers who are pregnant with boys usually have an increased appetite during pregnancy, especially for protein and calcium.