The boy dangled from the spike for a moment, then "the diaper opened and the baby fell to the ground, but at a much slower speed," a police officer said. "The diaper obviously lessened the impact of the fall and saved the baby's life."
"It was a miracle," said the officer who declined to be identified because she was not authorized to speak to the press. "He could also have been killed by one of the spikes."
The child was treated for minor fractures at the Hospital Memorial Sao Jose, where spokesman Gilberto Tenorio said he was in stable condition.
Police have opened an investigation to determine how the toddler fell out the window and "if parental negligence was one of the causes," the police officer said.
The Folha de S. Paulo newspaper quoted Caua's father, 23-year-old Alexandre Cesar Massaneiro as saying that his son climbed onto a sofa underneath the window he fell from - "something he had never done before."
"It wasn't the diaper that saved him," Massaneiro told the newspaper. "It was God."