William Tyrrell's biological mother has given birth to her sixth child, with the missing boy due to have turned 13 on Wednesday.
The woman, who cannot be named for legal reasons, is also celebrating her 36th birthday on Wednesday, having welcomed the birth of her baby.
She'd given birth to her second youngest in December, 2022, and is engaged to her current partner, according to her Facebook profile.
She was seen to be heavily pregnant with her sixth child in January this year.
A recent photo shows the mother with her toddler and newborn.
The woman's biological son William, who vanished without a trace while in the care of his foster parents at Kendall on the NSW mid-north coast in September 2014, would have celebrated entering his teenage years on Wednesday.
It will be ten years since he disappeared this September.
His biological mother regularly shares snaps of her other children.
In the hours following William's disappearance, the toddler's birth mother endured a police search of her home in Blacktown, western Sydney, which she shared with her then partner, who was also William's biological father.
William Tyrrell's biological mother, who cannot be identified, has given birth to her sixth child
In the years after William vanished, as he became Australia's highest-profile missing child case, his biological mother faced run-ins with police and unstable personal relationships.
In 2018, she revealed her heartbreak and agony over the mystery of her missing child in a TV interview, in which she admitted she felt 'like the worst mum in the world' after the 2014 disappearance, adding that whoever took William 'needs a bullet'.
William was removed from his biological mother and father at just seven months, in early 2012.
At the inquest into William's disappearance in 2019, the birth mother gave evidence that she had 'not given up on' getting William back after he was taken into the care of the Department of Family and Community Services (FACS) and given to foster parents.
Police inquiries into whether William's foster mother may have been involved in the boy's disappearance have been paused until after an inquest into his suspected death.
William's foster mother, who also cannot be named for legal reasons, has repeatedly denied any involvement in William's disappearance.
William vanished from his foster grandmother's home in September, 2014. He has never been found
William Tyrrell (pictured with his birth parents and older sister) was taken from their care and placed with foster parents before he disappeared