Lina Medina was just five years old when she gave birth to a baby boy in 1939.

Her parents - Tiburrello Medina and Victoria Losia - noticed Lina’s stomach growing after she complained about abdomen pains, and initially doctors believed she was suffering from a large tumour.

But the truth was even more frightening and bizarre.

The doctor explained that Lina was seven months pregnant

Just weeks later on May 14, 1939, Lina gave birth to a baby boy via a c-section, as her young pelvis was too small for a natural birth. 

Lina Medina, the youngest confirmed mother in medical history https://t.co/HsyFhxJjCY pic.twitter.com/hkGxT1fAMR

— Old Pics Archive (@oldpicsarchive) January 29, 2017

At five years, seven months, and 21 days of age, she became the youngest known person to ever give birth.

She named her baby Gerardo, after the doctor who delivered him. Gerardo was born a healthy 6lbs and would go on to live until he was 40 years old.

When Gerardo was born, the doctor discovered that despite Lina only being five years old, she had mature sexual organs and suffered from a condition called precocious puberty.

According to the Mayo Clinic, precocious puberty is when a child’s body begins changing into that of an adult (puberty) too soon. Puberty that begins before age 8 in girls and before age 9 in boys is considered precocious puberty.

While the family never officially spoke to the press, it was reported that Lina's mother noticed her daughter having periods from as young as three. 

Lina Medina, a most disturbing story.

In 1939, FIVE-yr-old Peruvian girl Lina gave birth 2 a healthy baby boy. A medical miracle#amwriting pic.twitter.com/mlqXm6Y619

— Enricoh Alfonzo (@Alfonzowords) February 1, 2017

Lina never disclosed who the father was, and initially, her father was suspected of rape and was arrested. He was released and the charges against him were dropped, because there was no evidence or witness accounts suggesting he was involved. He continued to maintain he had never had sex with his daughter, and he was not the father of her child.

Until the age of ten, Gerardo believed that Lina was his sister. He died in 1979 from a bone disease.

According to The Times of India, Lina, who has never spoken about the pregnancy, is still alive today, and is 86 years old.

How to answer the fraught question: ‘When are you having a baby?’ On Mamamia Out Loud. 

She went on to marry her husband Raul in the 1970s and later gave birth to a second son.

Lina’s story has throughout the years been accused of being a hoax, but local doctors maintain they have x-rays and biopsies to prove the five-year-old was pregnant. 

Lina is still the youngest person in the world to have ever given birth.