Business review website Yelp reported a wider fourth-quarter loss than analysts estimated Wednesday as it boosted spending on expansion into new markets.

The net loss was $5.32 million (8 cents per share), the San Francisco company said. Analysts on average were projecting a loss of 5 cents, according to data compiled by Bloomberg. Revenue was $41.2 million, compared with the $40.3 million average analyst prediction, while sales and marketing expenses jumped by 59 percent to $25.5 million.

Chief executive Jeremy Stoppelman has been pushing Yelp into more markets, especially outside the U.S. The company arrived in 26 new cities in 2012, and in the fourth quarter expanded into Poland and Turkey, bringing its business to a total of 97 markets in 20 countries worldwide.

“We still have questions about Yelp’s ability to profitably scale its business in its newer, including international, markets,” said Tom White, an analyst at Macquarie Capital USA.

Yelp declined as much as 6.2 percent to $21 in extended trading after the earnings report. The shares have gained 49 percent since the company’s initial public offering in March 2012.

First-quarter revenue will be $44 million to $44.5 million, the company said. That compares with the average analyst projection of $44.3 million.

Total reviews on Yelp’s sites, where consumers rate and comment on local businesses from hair salons to insurance agencies and doctors’ offices, increased 45 percent to more than 36 million at year’s end, while average monthly unique visitors grew 31 percent to about 86 million, Yelp said. The company’s mobile applications were used on about 9.2 million unique devices on average per month.

Yelp introduced mobile advertising in the fourth quarter, seeking to take advantage of the increasing number of users accessing the service on smartphones.

“We’re positive on Yelp’s ability to monetize its mobile apps over time given that Yelp’s mobile Web ads have higher engagement than desktop,” Kaizad Gotla, at analyst at JPMorgan Chase in New York, said in a report. “However, we do not view this as a driver of significant near-term revenue upside.”

Danielle Kucera is a Bloomberg writer. E-mail: [email protected]