Charlie Gard's mother Connie Yates lashed out at Great Ormond Street Hospital, where the baby has been treated, after a court overruled her wish to spend more time with the 11-month-old before he dies.
The hospital "denied us our final wish," Yates said in a statement after a judge on Thursday agreed with doctors that Gard should be moved to a hospice and life support should be withdrawn shortly thereafter.
Gard was born with a rare form of mitochondrial disease that causes progressive muscle weakness, including in key organs such as the heart.
Yates and Chris Gard, the boy's father, fought a five-month legal battle for him to be taken to the United States for experimental treatment.
But they gave up last week saying "time has run out" after they were shown scans that indicated that his condition had deteriorated too much.
They then asked for Gard to be taken to their home for his final days but were overruled by the hospital which said the ventilator keeping him alive was too bulky to fit through their front door.
A hospital spokeswoman said doctors had "tried absolutely everything" to accommodate their wishes.
But she said that "the risk of an unplanned and chaotic end to Charlie's life is an unthinkable outcome for all concerned and would rob his parents of precious last moments with him".
Gard's parents lost a series of appeals in British courts and the European Court of Human Rights in Strasbourg for him to be taken to the US.
Their legal battle led to offers of help from the United States and the Vatican, leading the hospital to ask the courts for a final assessment of any new evidence.