Estelle P. of Mississippi, at 9 years of age, gave birth to a baby boy on March 16, 1908. She had been menstruating since the age of 1, according to an archived newspaper article on Wikipedia. She was impregnated by her father. Following delivery, baby and mother were healthy.
The average age of menstruating onset for girls in the United States is 12.5 years old, but it is possible through variations in biology for girls to begin menstruating as young as a few months old. When this unusual condition of early reproductive maturity is combined with sexual activity, children potentially give birth to children. Worldwide, girls as young as 5 and 6 years old have successfully delivered healthy babies.