Originally Posted by ktbb

As you sew your seam, GENTLY pull the sweater material both in front of and in back of the needle to stretch the fabric as you add the thread - let the feed dogs move the fabric thru, all you do is gently stretch the fabric evenly. This builds in stretch. Also use a medium size zigzag stitch...when the seam is finished, you won't notice that it's a zigzag and you'll have plenty of stretch in it. If the fabric looks a little weird when you're finished, wash the garment and the fibers will go back in place.