Let's say you're 8 weeks pregnant (not showing yet) and currently wearing a small but if wish to wear this shirt all through pregnancy, you may consider ordering a medium. Because later in pregnancy, you may find yourself fitting into medium shirts better. Upon receiving the medium, it may fit a little oversized/large at first, however, as pregnancy progresses and your cute baby bump grows, you will be happy that you ordered the medium. **If you care more about the fit for your big announcement in the earlier stages of pregnancy, and prefer the shirt to fit best upon receiving, only then would you probably order the small. We have included a size chart in the photos section that may also help you decide on a size by finding your chest measurements on the chart and comparing.