Corinna Schumacher also asked the media to leave her family in peace after German reports said on Monday there had been a slight improvement in the former driver's condition, hours after Grenoble hospital had issued a bulletin saying he was still stable but critical.
"Please support us in our joint struggle with Michael," Corinna said in a statement. "It is important to me that you relieve the doctors and the hospital so they can work in peace.
"Please trust their statements and leave the hospital. Please also leave our family in peace."
They were Corinna's first public comments since a December 30 statement in which she thanked the medical team for their efforts and expressed gratitude to fans around the world for their outpouring of support.
Schumacher, a seven-times Formula One world champion, suffered brain injuries when his head hit a rock in France on December 27.
He has been in an induced coma since then and has undergone two operations in Grenoble.
The hospital and the German's management have repeatedly asked the media to respect his privacy.
The medical team have held news conferences and issued periodic bulletins on his condition including one on Monday that said: "The clinical state of Michael Schumacher is stable as he's under permanent care and treatment.
"However, the medical team in charge stresses that it continues to assess his situation as critical."
Bild, Germany's best-selling newspaper, reported on Tuesday under the headline 'First hopes for Schumi' that the former driver nearly died twice last week.
It added that doctors were now more optimistic he would survive.
"Twice in the last week it looked like Schumi would lose the fight for his life," Bild wrote.
"The brain scan on Friday was 'catastrophic', Bild has learned from medical sources. But after the readings stabilised towards the weekend the doctors are now confident he will make it."
Last week Schumacher's agent Sabine Kehm urged journalists to stay away after security guards said they intercepted a reporter disguised as a priest who was trying to get into his room.
Schumacher, who turned 45 on Friday, is the most successful Formula One driver of all time with 91 race victories.
He left the sport last year after a disappointing three-year comeback with Mercedes following an earlier retirement from Ferrari at the end of 2006.
French newspaper Le Dauphine Libere reported on Tuesday that the camera Schumacher had on his skiing helmet was recording when he crashed.
The newspaper said investigators had footage that will be useful to understand the circumstances of the accident. The prosecutor in Annecy is due to hold a news conference on Wednesday.
(Additional reporting by Gregory Blachier in Paris, editing by Tony Jimenez)