President Barack Obama has caught a woman who was apparently about to faint while he hosted a press conference at the White House.

"I got you," he told the woman as she began to swoon during a Rose Garden event to address glitches in his administration's healthcare-insurance website.

"This happens when I talk too long," the president quipped.

The woman, Karmel Allison, recovered and said later she was a pregnant diabetic, tweeting: "Thanks, @BarackObama for catching me!"