NEW YORK — Maternity retailer Mothers Work Inc. delivered a successful first quarter, as income skyrocketed 85.2 percent on strong holiday sales, gross margin improvement and new accounting rules.

In addition, the Philadelphia-based company named Ed Krell as its chief financial officer, replacing Michael F. Devine, who left the firm to join Coach in November. Krell will be responsible for all financial reporting, planning and analysis and control. He will report to Dan Matthias, chief executive officer of MW, beginning Jan. 28. He previously served as cfo of London Fog Industries.

For the three months ended Dec. 31, income rose to $2.5 million, or 44 cents a diluted share, compared with $1.4 million, or 28 cents, recorded in the year-ago period. Net sales for the quarter improved 11.4 percent, to $114.4 million from $102.7 million, but declined 2.5 percent on a comparable-store basis. The company said a net increase of 29 stores and the acquisition of the 170-store iMaternity organization in October led to the sales increase.

“New stores, the [iMaternity] acquisition and the Internet all contributed,” Rebecca Matthias, president and chief operating officer, said in a telephone interview. “Maternity is a microcosm of the world. Almost every woman passes through our niche.”

In a statement, Rebecca Matthias said that the strength of sales during holiday paved the way for the improved results “in spite of acquisition-related expenses.” Looking ahead, she said the company’s focus would be merchandising and improving its gross margin, which had a year-over-year increase of 2.5 percent due to better sourcing.

Mothers Work currently operates 939 maternity locations under the nameplates A Pea in the Pod, Mimi Maternity and Motherhood Maternity. The company plans to add another 60 to 70 doors this year.