The co-founder of the world's largest social network used a Facebook post Friday to announce that Chan is pregnant with a healthy baby daughter. He didn't say when the baby is due.
"Cilla and our child are both healthy, I'm extremely excited to meet her and our dog Beast has no idea what's coming," Zuckerberg wrote. "In our ultrasound, she even gave me a thumbs up "like" with her hand, so I'm already convinced she takes after me."
Zuckerberg, 31, also said the couple had suffered three miscarriages over the last two years. He acknowledged in his post that many people are reluctant to speak publicly about miscarriages. But he said he and Chan, 30, decided to share the information after hearing from friends who had similar experiences and ultimately were able to have children.
"Most people don't discuss miscarriages because you worry your problems will distance you or reflect upon you - as if you're defective or did something to cause this. So you struggle on your own," Zuckerberg wrote. "It's a lonely experience."
The social media mogul added, "In today's open and connected world, discussing these issues doesn't distance us; it brings us together. It creates understanding and tolerance, and it gives us hope."
He said the couple, who married in 2012, hopes to encourage other parents who may be struggling with difficult pregnancies.
"We hope that sharing our experience will give more people the same hope we felt and will help more people feel comfortable sharing their stories as well," he said.
Zuckerberg also said: "Our good news is that our pregnancy is now far enough along that the risk of loss is very low and we are very hopeful."
So will they be posting baby pictures? Zuckerberg didn't make any promises, but he wrote: "We're looking forward to welcoming her into the world and sharing more soon when she's ready to come out and meet everyone!"
Written with inputs from AP