On May 14, 1939, a 5-year-old Peruvian girl named Lina Medina gave birth in one of the biggest medical mysteries of its time, becoming the youngest mother in history in the process. Although some people have claimed it was a hoax, many doctors over the years have verified it based on both photographic and medical evidence.

In April of 1939, Lina’s mother brought her in to see a doctor because of her abnormally protruding belly. She was afraid that evil spirits had possessed her daughter. The doctor was worried that the child had an abdominal tumor growing inside her. As a medical examination showed, they were both wrong.

It turned out that Lina had a rare condition known as precocious puberty, which caused her to go through puberty at a much younger age than normal. It occurs in approximately 1 out of every 10,000 children. Lina had her first period at the age of three.

Doctors were worried for both the mother and the infant growing inside her. They anticipated all kinds of things going wrong. When her time came, she was given a Caesarian section. To everyone’s amazement, both mother and child pulled through the procedure without trouble, and both of them were healthy.

The baby was raised by Lina’s parents, alongside Lina, who, of course, was more interested in playing with her dolls than being a parent. Lina never revealed who the father of her child was, nor anything about the circumstances under which she became pregnant. Dr. Gerardo Lozada, the doctor to whom Lina’s mother first took her, has called the case “the most incredible thing” he had ever witnessed in the course of his entire career.