Electronic manufacturing services company Plexus Corp. said Wednesday its fiscal first-quarter profit grew sharply as revenue increased, but offered a less rosy forecast.

"Looking ahead to the second half of the fiscal year, we currently anticipate meaningful challenges in the fiscal third quarter due to a confluence of issues," said Dean Foate, president and CEO, in a statement. These include the winding down of two manufacturing programs and a production delay in two programs for one of its customers, the Coca-Cola Co.

For the three months ended Jan. 1, the company earned $25 million, or 61 cents per share, up 40 percent from $17.8 million, or 44 cents per share, in the same period a year earlier.

The company's forecast had been for earnings between 56 cents and 62 cents per share.

Revenue rose 32 percent to $565.8 million from $430.4 million.

Analysts, on average, were expecting earnings of 59 cents per share on revenue of $565.6 million, according to Factset.

For the fiscal second quarter, Plexus expects earnings of 53 cents to 58 cents per share on revenue of $540 million to $570 million.

Analysts are predicting earnings of 55 cents per share on revenue of $557.9 million.

"While the fiscal first quarter met our expectations for modest sequential growth, the mid-point of the guidance suggests a modest decline in revenues in the fiscal second quarter of 2011," Foat said.

He added that the second quarter will be dragged by higher structural seasonal operating costs, including salary adjustments.

For the third quarter, Plexus expects revenue to be down from the second quarter.

Its shares were unchanged in after-hours trading after initially tumbling following the release of the earnings report.