Top fashion designer Donna Karan is to release a maternity range, according to reports.Released as part of the DKNY 20th anniversary celebrations, the items will be entitled the Happy Birth-Day Collection.Available to lucky ladies in America, the 18-piece range promises to be sexy and comfortable for mums-to-be.The main colours featuring in the range include white, black and grey, which will be spread across the trousers and skirt collection.WWD reports that the pieces will be for sale in DKNY shops and famous department store Bloomingdale's.Donna's Fall 2008 collection includes a variety of loose-fitting garments, with the designer focusing on natural tones such as green, purple and brown.Plunging necklines also dominate this autumn's trends.She also shows a love for luxurious fabrics, with silk and velvet dominating a number of items.Opaque tights are in vogue, which are coupled with sophisticated black heels.(c) 2007 Adfero Ltd.