“Zack and I are excited to announce that our identical twin girls were born early this morning,” she wrote to her over 1 million followers on Twitter. “Our whole family is doing great! @zackbogue”

“Thanks to everyone for all of the support and well wishes throughout my pregnancy,” she added on her Tumblr, the blogging site Yahoo bought in 2013.

In September, Mayer announced that she and her husband, investor Zachary Bogue, were having twin girls. “The twins part was quite a surprise, because I have no family history of twins or any other predisposing factors,” she wrote on Tumblr at the time.

Mayer, 40, was pregnant when she joined Yahoo as CEO in July 2012. She gave birth to a baby boy in September that year and was criticized for taking just two weeks off. But later she sweetened Yahoo’s parental leave perks, including giving a $500 stipend to parents to spend on their newborns.

Mayer has said that she plans to take just two weeks leave once again, despite Yahoo’s eight available weeks. “Moving forward, there will be a lot to do for both my family and for Yahoo; both will require hard work and thoughtful prioritization,” she had wrtitten on Tumblr.

Yahoo shelved plans on Wednesday to spin off its stake in Chinese e-commerce giant Alibaba amid pressure from activist investors worried about billions of dollars in taxes. Instead, it said it is looking at creating a separate company to hold the rest of its assets.

Reuters contributed to this report.