Medical products makers Baxter International Inc and Covidien Plc posted stronger-than-expected quarterly results, boosted by robust demand, and they raised their full-year outlooks.

Shares of both companies were up about 3 percent in trading before the market opened.

Baxter said its first-quarter net earnings came to $577 million, or 98 cents per share, compared with a year-earlier loss of $60 million, or 11 cents per share, that included a big charge for the recall of its Colleague pump.

Analysts on average were expecting earnings of 93 cents a share, according to Thomson Reuters I/B/E/S.

Revenue rose to $3.28 billion from $2.93 billion, led by a 20 percent sales increase in Baxter's medical products business, which sells IV therapies and injectable drugs.

Covidien reported net earnings rose to $455 million, or 91 cents per share, in second quarter ended March 25, from $413 million, or 82 cents a share, a year earlier.

Net sales rose 10 percent to $2.80 billion. Sales of medical devices increased 16 percent to $1.88 billion, and pharmaceutical sales fell 4 percent to $490 million.

The company now expects fiscal 2011 net sales to grow 8 percent to 11 percent, including foreign exchange at current rates, compared with its earlier growth forecast of 6 percent to 9 percent.

Shares of Covidien were up 2.6 percent at $55.25 in trading before the market opened, while Baxter gained 3.3 percent to $56.30.

After the market closed on Wednesday, Boston Scientific Corp posted a stronger-than-expected profit for the first quarter even as sales slipped, as it cut expenses. The cardiovascular device maker also raised its earnings per share forecast for the full year.

The company's shares rose 2.4 percent to $7.25.

(Reporting by Debra Sherman; Editing by Lisa Von Ahn)