Twitter showed modest growth in the number of active users on the social network Tuesday, but a gloomy forecast and revenues that missed Wall Street expectations sent the shares tumbling in after-hours trading.

The increase in users, which reversed a decline in the previous quarter, was a rare positive for the ailing company. But less than stellar predictions for advertising revenue over the coming months showed just how far Twitter has to go. The stock plunged more than 12 percent when its earnings report came out, after rising nearly 4 percent in regular trading.

Twitter's focus on the here and now made it the darling of news junkies, but the social network has struggled to grow its customer base -- and thus its advertising revenue.

Concerns over whether growth had stalled at Twitter appeared to be confirmed when the company in February said its monthly active users had actually shrunk over the last three months of 2015.  The monthly user figures reported Tuesday helped relieve those worries somewhat: The company reported 310 million monthly active users, up from 305 million the previous quarter.

"On the usage front, Twitter desperately needs to get its momentum back," said Debra Williamson, a principal analyst at eMarketer. The firm recently downgraded its expectations for Twitter's 2016 annual global ad revenues from $2.95 billion to $2.61 billion, in part due to concerns over slow user growth.

Twitter indeed predicted that it would earn somewhere between $590 million and $610 million in revenues in the second quarter of this year, far short of the $677 million expected by the analysts polled by Bloomberg.

For the first three months of the year, the company reported $595 million in revenue, missing the $608 million Wall Street had expected. Some of the softness came from big brand marketers -- especially in the technology and retail sector -- that did not increase ad spending as quickly as Twitter expected, executives said. Video advertising, however, was strong, they said.

Overall, Twitter said it saw a net loss of $80 million, or 12 cents a share, which was a bit better than analysts had forecast.

The specter of stagnant user growth has loomed over Twitter for a while, but cast an especially dark shadow over the past year: Shares lost two-thirds of their value in a slide tipped off by a disappointing earnings report in the first quarter of 2015.

Co-founder Jack Dorsey returned to take the reins as chief executive last year, first on an interim basis in July and then officially in October. Since his return, Dorsey has shaken up Twitter's top ranks while trying to broaden the network's appeal with new features, including Twitter's Moments -- which highlights tweets about daily top-trending topics -- and also doubling down on the real-time nature of Twitter by betting on live video.

Earlier this month, Twitter reached an agreement with the NFL to stream 10 full Thursday night football games. "Its deal with the NFL caught a lot of people by surprise," said eMarketer's Williamson, who called it "the kind of bold move" that could help push new usage growth.

But Twitter's user-generated live streaming product Periscope faces stiff competition from Facebook, which has recently launched its own service.

"One wonders whether or not Facebook's push in this area is going to have -- or perhaps already had -- a negative impact on Twitter, and if so, what are they doing about it?" said Scott Kessler, deputy global director for equity research S&P Global Market Intelligence.