From olden times in Japan, pregnant woman put a white cloth called "Haraobi" around the abdomen wishing for an easy delivery. It is quite useful to keep you balanced as well as warm. Nowadays, some people wear a maternity girdle instead of a Haraobi. But a Haraobi is easier to adjust to your size. Many Japanese visit shrines and pray a God for an easy delivery, and buy Haraobi there...After delivery, you can use your Haraobi again to regain your shape, and cut it in small pieces and use it for your baby's nappies. However, these days most people seem to be using handy disposable diapers.
Even though I lived in Japan, I'd never heard about it, and I bet a lot of other people have no idea what it is, either. There isn't much information about it in English, but you can read about it in Japanese. There's too much information to translate it here quickly, but maybe one of those online translation thingies would be decent enough.