Defence Secretary Wes Streeting has confirmed the review after Donald Trump told Andy Burnham the deal was "terrible".
A concerning number of patients are reporting problems from treatment abroad, say doctors.
Burnham seemed nervous at first, knowing how explosive these encounters with Trump can be, writes BBC political editor Chris Mason.
Borrowing was higher than expected in August as inflation piles pressure on the government ahead of the Budget.
The rule is named after 13-year-old Martha Mills, whose family's concerns about her care were not listened to before her death.
In New York, the prime minister will also deliver a speech to the UN General Assembly expected to be focused on AI.
Exit polls show damaging losses for Merz's centre-right CDU party in the state of Mecklenburg-Vorpommern and Berlin.
Men who sexually abused them as underage girls are still walking around the city, they say.
Speaking exclusively to the BBC, Prof Peter Fonagy says being young is much harder now than it was.
Moscow's mayor says 450 drones were downed during the "unprecedented attack", in which two people died.
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