Secondary sexual characteristics

Some of these changes get a special name.

A deeper voice, facial and chest hair in boys, breasts in girls: these are not directly part of reproduction. But they help tell males and females apart. So they are called secondary sexual characteristics.

They are natural signs that the body is getting ready for adulthood. They mark the start of puberty.

Puberty is the stage when an adolescent's body changes, outside and inside, to become an adult who is able to reproduce.

Being able to does not mean being ready. Becoming a parent is for grown-ups, many years later. That is why the book's project calls child marriage a social evil: it harms children's health and their whole future, especially girls'.