The Ruffled Baby Romper pattern provides two methods of finishing - with a snap crotch or with a fixed, sewn crotch. Here is an alternate way to sew the final seam of a fixed-crotch romper that requires just a little more skill than the easy method given in the PDF pattern, but allows a smooth, seamless finish for the entire romper.
The existing easy method instructs you to line up the front and back seams and stitch through all 3 layers, the front, the front liner, and the back, and then to finish the seam using a serger or other finish method. Quick and easy, and the finish looks like this on the inside.
To instead finish with the smooth method, you will turn the raw edges of the romper front main fabric and romper front liner to the inside by 1/2", so the raw edges are inside the gap between the liner and main fabrics.
From the right side of the romper, stitch across close to the folded edge of the romper front, catching the folded edge of the liner as you go.
Just a note also on matching the crotch seams for any finish method. Before you worry your front and back are mismatched, realize that the stitching line, where you will be joining the front and back, is ½” from the raw edge of the fabrics. Because the pieces are different shapes, they do not in fact match up at the very edges, but at the 1/2" mark where you sew them together, they will.
Enjoy sewing your Ruffled Baby Bubble Romper!