The Prime Minister has come under fire as the winter crisis has seen delays to admissions and tens of thousands of operations being cancelled amid unprecedented pressure on hospitals.
Health service bosses have said the NHS is at “bursting point”.
But Mrs May said there were winter pressures “every year”, adding: “The NHS has actually been better prepared for this [sic] winter pressures than it ever has been before.”
On the subject of the delays to NHS services, the PM told the BBC’s Andrew Marr Show cancelling operations was “part of the plan”.
“Of course we want to ensure that those operations can be reinstated as soon as possible, but it’s about making sure that those who most urgently need care are able to get that treatment when they need it,” she said.
Mrs May was challenged about the case of Leah Butler-Smith, who waited more than four hours in an ambulance with her mother – who had suffered a stroke – at Broomfield Hospital in Essex.
She said she said that “of course nothing’s perfect and there is more for us to do”.
“We have planned for the winter pressures this year,” she continued.
“We did put some more money in and there has been planning and hospitals have been dealing with it in different ways.”
Mrs May would not be drawn on the future funding of the NHS, after Health Secretary Jeremy Hunt suggested a 10-year funding plan.
An A&E doctor dismissed Mrs May’s claims about the preparedness of the NHS, telling Sky News the assertion was “misleading, disingenuous nonsense”.
“The system I’ve been working in in recent days and weeks seems under-resourced, under-funded and under-staffed,” Adrian Harrop said.
“It is in no sense prepared or an adequate system to meet the needs of the population who require it.”
Meanwhile, Labour’s Jonathan Ashworth told Sky News the crisis was “entirely predictable and entirely preventable”.
“We’re now in the eighth year of underfunding in the NHS. We’ve seen cuts to district health nurses, we’ve seen 14,000 beds lost from the NHS,” the shadow health secretary said.
“So the crisis we’re seeing with elderly people being treated in the backs of ambulances in this freezing cold weather languishing on trolleys is a result of decisions made by this Tory government and this Prime Minister.”
Figures released earlier this week revealed almost 17,000 patients waited more than 30 minutes in ambulances at accident and emergency departments in England during the week up to New Year’s Eve – up 42% from 11,900 in the previous week.
NHS England figures showed the bed occupancy rate in hospitals reached 91.7% during the festive period – 85% is considered safe.
Increased pressures on front-line services were mirrored in the NHS 111 service, which received a record 480,400 calls – up 21% from 396,300 in the previous week.
Chief executive of the Royal College of Nursing (RCN) Janet Davies said the figures showed “that almost every day last week, NHS hospitals in England were at bursting point”.