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.

Xi, Putin hail ties in video call as Ukraine war nears anniversary
Israeli strikes kill 21 in Gaza, health officials say
Nestle widens infant formula recall after France lowers toxin level
UN Chief warns two-state solution slipping away amid West Bank expansion
Pakistan sends helicopters, drones to end desert standoff; 58 dead