I agree and thought about including a third choice, "I don't know" or something similar. In the end I decided to create the example with the same amount of choices currently available in Avast. However, using a third choice might go something like this:
Current Avast, is she pregnant?
[√] Yes
[√] No
[√] Not sure
Future Avast, is she pregnant?
o Yes
• No
o Not sure