Yes, the best way to backup your data is to use the syncing feature, to make sure you data backups are always up to date.

Or you may backup to the SD card.   Access the backup/restore options from the Settings screen (access from the Main screen of the app by pushing the menu button on your phone). Your data will be stored in the com.hewittsoft.baby directory. You may then later restore the data from backup if you need to with one click.  Or you can use transfer the backup data to a new phone to bring your Baby ESP data with you.

To keep a more readable backup, you can email yourself your data in CSV format or in a printable format.