Remember when Gisele Bundchen was pregnant? It's been a while, but here is a great casual look that you can make your own quite easily.
Take a pair of cargo pants. If you are shorter than Gisele (likely), then maybe try a pair of jeans. Add a simple long-sleeved shirt. If you (and your back) can wear heels, then add a pair of those too! Otherwise, a pair of flats will do nicely as well.