Yahoo Chief Executive Marissa Mayer is pregnant with identical twin girls, likely due in December, she said in a blog post.
"Since this is a unique time in Yahoo's transformation, I plan to approach the pregnancy and delivery as I did with my son three years ago, taking limited time away and working throughout," Mayer wrote in a post early Tuesday.
Yahoo said in its corporate blog that the company was "extremely happy" for Mayer and supported her plans and approach.
Mayer's pregnancy comes at a critical time for Yahoo. The company is preparing to spin off its stake in Alibaba Group Holding Ltd to investors and is also looking at cashing in its stake in Yahoo Japan Corp.
Mayer, 40, was pregnant when she joined Yahoo as CEO in July 2012 and gave birth to a baby boy in September that year. She worked from home after the birth and came back to the office just two weeks later.
Her comments at the time that she did not plan to take extended maternity leave stoked a debate about whether her example would help or hurt the cause of women in the workplace. Since taking the helm, Mayer has sought to boost morale at the nearly two-decade-old Internet company, eliminating bureaucracy and introducing perks such as free food.