Fits up to 8 lbs.  Interlock knit works best for these sleepers.

With right sides together, sew/serge sleeves to sleeper front, repeat for back. Sew ribbing on sleeves. With facing folded back 1" wrong sides, to wrong sides, pin front sleeper to back sleeper matching sleeve hems, underarm seams, and crotch seam, overlapping facing at crotch 1". Stitch from sleeve hem, down side, around feet and crotch, and end at the other sleeve. Fold 3 inch ribbing in half lengthwise and then widthwise. Trim center front ribbing widths to 1/4",  tapering to full width at center back.  (foldline is center back and raw edges are center fronts). Unfold ribbing widthwise and divide ribbing into four equal sections.  Mark sections with three pins. Divide sleeper neck into four equal section and mark with two pins - center back seam need not be marked with a pin. With right sides together,  pin raw edges of ribbing to sleeper neckline,  matching pins and center back seam. Center front ribbing ends should be 1" in from front seamline.  Fold facing over ribbing covering ribbing ends. Pin. Stitch,  stretching ribbing to fit sleeper neckline. Trim corners and turn right side out. Sew three button and button holes down the front of sleeper opening. You may also use snaps,  sew-on-snaps or Velcro instead of buttons.