Yahoo CEO Marissa Mayer is pregnant with identical twins.
Mayer said on her blog that she and her husband are expecting twin girls in December.
"I have some exciting news to share -- I'm pregnant!" wrote on Tumblr late Monday.
She says that she will take some limited time away but work during the pregnancy as she did with her son's birth three years ago. Yahoo Inc. executives are aware of her pregnancy.
The news comes at a busy time at the Sunnyvale, California, company.
Mayer has been trying to engineer a turnaround since Yahoo hired her away from Google, but has made limited progress. Yahoo's net revenue has decreased or been unchanged from the previous year in eight of the previous 10 quarters.
Company shares have soared since she took over, mainly because of Yahoo's large stake in one of China's hottest Internet companies, the Alibaba Group.
Pressured by shareholders, Yahoo earlier this year filed plans to spin off its remaining 384 million Alibaba shares into a separate company that will be called Aabaco. Yahoo is still awaiting approval from the Internal Revenue Service to do the split on a tax-free basis, which the company expects to occur this year.
Yahoo's Alibaba stake is currently worth nearly $32 billion, representing most of Yahoo's market value.
Without the Alibaba stock in its investment portfolio, Yahoo will have to start boosting its revenue or risk of shareholder unrest.
Three years ago, Mayer announced she was pregnant with her son a few hours after Yahoo hired her as its third full-time CEO in less than a year.
Her decision to spend just two weeks away, working from home, before returning to Yahoo's offices was criticized by some who said that it set unfair expectations for other working mothers.
A few months later, the company expanded its parental leave policy for both mothers and fathers and added other perks for new parents.