• by Mark Walsh  @markfwal, May 2, 2013

LinkedIn on Thursday reported revenue increased 72% in the first quarter, benefiting again from solid growth across its three key business lines.

The company’s net income for the quarter was $22.6 million, or 20 cents a share compared with $5 million, or 4 cents a share, a year ago. On an adjusted basis, LinkedIn reported a profit of 45 cents a share, up from 15 cents a year earlier.

Revenue for the professional networking site rose to $324.7 million from $188.5 million in the year-earlier period. Analysts, on average, had expected LinkedIn to report an adjusted profit of 31 cents a share on revenue of $318 million.

Sales from LinkedIn’s recruiting services business, increased 81% from a year ago to $184.3 million and accounted for 57% of total revenue. Marketing Solutions -- its advertising arm -- saw revenue rise 56% to $74.8 million, or 23% of overall revenue. And sales from premium subscriptions grew 73% to $65.6 million, or 20% of overall revenue.

U.S. revenue amounted to $201.4 million, or 62% of first-quarter revenue, while international markets contributed $123.3 million, or 38%. That’s the same split as in the fourth quarter.

"Q1 was a strong quarter for LinkedIn with member engagement and financial results reaching record levels," said Jeff Weiner, CEO of LinkedIn.

LinkedIn has continued to take aggressive steps to enhance its content offerings and boost user engagement. These included its $90 million acquisition of news aggregator app Pulse last month and the launch of an upgraded search service, which it says has so far lead to increased search activity on the site.

These moves follow a series of initiatives rolled out in the fall to keep users engaged, including the start of a blog network featuring high-profile “influencers,” redesigned profile pages and the ability for people to recommend each other’s skills via an Endorsements feature.

Those efforts helped LinkedIn increase member page views (including mobile) 63% in the quarter, roughly on par with the 67% rise in the fourth quarter, based on the company’s internal metrics.

With 30% of LinkedIn’s traffic now coming from mobile devices, the company has also been ramping up services. Besides acquiring the Pulse app, it has begun testing in-stream ads on tablets and smartphones, and in April, released a dedicated iOS app for managing LinkedIn contacts as well as an updated version of its main app.

During the quarter, LinkedIn increased its overall member base to 218 million, up from 200 million at the end of 2012, and 161 million a year ago.

The company projected revenue for the second quarter between $342 million and $347 million. That estimate fell below the forecast of $359 million of analysts polled by Thomson Reuters, causing LinkedIn shares to fall about 10% in after-hours trading following the earnings report. The stock had closed Thursday at $201.67, up 3.5%. 

In the conference call, LinkedIn CFO Steve Sordello acknowledged the company ‘s ad business in the second quarter faces a tough comparison with the year-earlier period when it landed a number of large, one-time deals. He said the business is also going through a transition as it incorporates ads into users’ news feeds.