BOSTON - Tom Brady played through a concussion last year on his way to a fifth Super Bowl title, according to his wife, supermodel Gisele Bundchen.

The injury, which was not reported by the team, left her worried about how long he should continue to play football.

Asked if she wanted the New England Patriots superstar quarterback to retire, Bundchen expressed concern "as a wife" in an interview on CBS This Morning that aired on Wednesday.

"He had a concussion last year. He has concussions pretty much every..." she said, before cutting herself off.

"I mean, we don't talk about it. But he does have concussions. I don't really think it's a very healthy thing for anybody to be going through."

Brady sat out the first four games of last season as punishment for his role in the "Deflategate" scandal and missed practice late in the season for leg, thigh and ankle injuries.

However, he was not listed on the league-required injury reports for concussion at any point during the 2016 calendar year or the 2016 season.

The NFL requires "significant or noteworthy" injuries to be reported, regardless of whether a player is expected to miss playing time, and says honest reporting of injuries "affects the integrity of the game".

The Patriots and Brady's agent declined to respond to Bundchen's comments on Wednesday.

NFL spokesman Brian McCarthy said league officials reviewed all reports from independent neurotrauma consultants and athletic trainers who worked at Brady's games during the 2016 season.

"There are no records that indicate that Mr Brady suffered a head injury or concussion, or exhibited or complained of concussion symptoms," McCarthy said.

"Today we have been in contact with the NFLPA (the players' union) and will work together to gather more information from the club's medical staff and Mr Brady."

The league is especially, though belatedly, sensitive to concussions, which have been linked to a brain disease that leaves former players forgetful, violent or suicidal.

The NFL has agreed to pay $1 billion to retired players who accused the league of concealing the link between football and brain damage.

Chris Nowinski, a founder and the CEO of the Concussion Legacy Foundation, said only a small percentage of concussions are diagnosed, in the NFL and elsewhere.

"I'm most surprised that people think it's really news that an NFL player had a concussion but it wasn't diagnosed and it wasn't reported," he said on Wednesday from a Brain Trust conference at Harvard Medical School.

"But it is a great opportunity to educate people that it's very dangerous to play through a concussion. And if you have an opportunity to get off the field and get it taken care of, you need to take it."

By winning his fifth NFL title at the age of 39 - leading the biggest Super Bowl comeback in history - Brady has already defied age and cemented himself among the league's all-time greats.

He has long said he wanted to keep playing until his mid-40s, but he told ESPN in an interview published this week that he would continue beyond that if he was able to stay healthy and productive.

But Bundchen balked at those plans when asked by CBS host Charlie Rose about her husband's intentions.

"That kind of aggression all the time, that cannot be healthy for you," she said.

"I'm planning on him being healthy and doing a lot of fun things when we're like 100, I hope."

Associated Press