I'm not sure if that's a word but I used it in Scrabble yesterday so it should be okay.

The youngest mother whose history is authenticated is Lina Medina, who delivered a 6½-pound boy by cesarean section in Lima, Peru in 1939, at an age of 5 years and 7 months. The child was raised as her brother and only discovered that Lina was his mother when he was 10. And you thought teenage pregnancies complicate matters.

Girls such as this suffer from a hormonal imbalance, or precocious puberty, which is characterized by premature secondary sex characteristic development. In a small percentage ovarian and uterine development appropriate for fertility also occurs, making pregnancy possible. Lina, for instance, began menstruating at age 3.