The baby of Shamima Begum, a British-born teenager who fled London to join the IS, has died in Syria.
The death has been confirmed by the US-backed Syrian Democratic Forces, who declined to specify how or when it happened.
According to the medical certificates obtained by the BBC, the three-week-old boy died of pneumonia.
Shamima, who was stripped of her UK citizenship despite her wish to return, had previously lost two other children, apparently from illness and malnutrition.

US, German scientists win Nobel medicine prize for work on light and brain
Nigeria military aircraft crashes with 32 aboard
At least 22 dead after boats collide on Congo river
Spanish PM Sanchez calls snap election for November 29
Hundreds of French schools stay closed ahead of nationwide day of student protests