That-time-o-the-month skivvies

Step 4 Zig zag in

Now, use a zig zag stitch along the side, and even along the top and bottom if you're ambitious. Zig zag is better than a straight stitch for stretchy spots, since it has some give. It turns out that my machine, a 1936 Singer 15-91 only does straight stitch, so I use a vintage zig zag attachment that actually works really well.