Yahoo CEO Marissa Mayer worked from her hospital bed shortly after having twins

Yahoo CEO Marissa Mayer's work ethic is near legendary.

And a recent report by the WSJ's Doug MacMillan shares another interesting bit of information that illustrates just how hard she works.

Late last year, Mayer was pregnant with twins. At the same time, she was pulling through one of the toughest periods of her time at Yahoo, running three-day meetings and addressing the media - right until the day before she gave birth to the twin babies.

But after having kids, Mayer remained closely in touch with Yahoo's management, even finding a way to speak with Yahoo chairman Maynard Webb on the phone from her hospital bed, the WSJ report says. The two discussed the company's next steps on the phone, and soon announced that it would explore a sale of its core internet business.

Given Yahoo was under immense pressure from activist investors to come up with a decision that's easily one of the most important in company history, it's not hard to see why Mayer wanted to work from the hospital. But it also sheds light on the crazy hours Mayer is known for working.

One former Google executive once told us, "[Mayer] will literally work 24 hours a day, 7 days a week," while Salesforce CEO Marc Benioff recently called her "completely magical."

PayPal cofounder and Affirm CEO Max Levchin even called her "the hardest working CEO in Silicon Valley, bar none."

Not everyone is a fan of Mayer's workaholic-like hours. Some people criticize her for setting a bad example for all working mothers in the US who don't get guaranteed paid maternity leave.

But Mayer believes she needs to be an exception as CEO of the company, and recently shared some data to show the rest of the company is not affected by her actions.