Mandel Ngan/Getty Images President Barack Obama thinks men might have something to do with the so-called tampon tax.

WASHINGTON -- President Barack Obama said Friday he had "no idea" why many states tax tampons and menstrual pads as "luxury items." Well, he does have one idea.

"I suspect it's because men were making the laws when those taxes were passed," the president told Ingrid Nilsen in a series of interviews with YouTube stars in the White House.

Nilsen pointed out that 40 states require people to pay sales tax on feminine hygiene products, even though states often allow exemptions for "necessities." Tampons and pads, it turns out, are not considered a necessity in those states for sales tax purposes.

That seems wrong, Nilsen said, since she doesn't "know anyone who has a period that thinks it's a luxury."

"I think that's fair to say," Obama said, joking that his wife, Michelle Obama, "would agree with you on that." He said he hadn't known about the issue before.

Some have argued that controversy over the so-called tampon tax is overblown and implies that there is a specific tax on feminine hygiene products, versus broader sales taxes that also apply to those products.

Still, the movement to exempt feminine hygiene products from sales taxes has gone worldwide.

Canada's government stopped taxing feminine hygiene products last July, and women in the United Kingdom have protested to do away with their own "tampon tax." A Change.org petition led by Cosmopolitan to end sales taxes on feminine hygiene products garnered more than 40,000 supporters.

After the question, Obama pivoted the conversation to women's health more generally, and talked about his efforts to ensure health insurance coverage for birth control and pregnancy.

"Women should not be at a disadvantage in the health care system," he said.