A pregnancy tracker for you and for him.
Questions, bugs, or ideas: jameszamora94@gmail.com. It helps to include your iPhone model, your iOS version, and the app version shown in Settings › App.
Open Settings › Sharing › Partner and tap Invite partner, then send the link however you like. They tap it on their own iPhone with Tether installed. They will see everything you log, and cannot change it. You can stop sharing at any time from the same screen.
Both phones need to be signed in to iCloud, and the invite has to be opened on the partner's phone, signed in to their own Apple Account. An invite opened on the phone that sent it will not do anything.
On your iPhone, and in your own iCloud account. There is no Tether account and no Tether server. See the privacy policy for the details.
Turn on Settings › Sharing › Sync with Apple Health, and check that Tether is allowed to read Weight, Heart Rate and Blood Oxygen in the iPhone Settings app under Privacy & Security › Health › Tether.
Yes. Settings › Sharing › Export my data saves everything you have logged as a spreadsheet file.
Settings › Sharing › Erase all data removes your entries from the phone and from iCloud. Deleting the app removes the local copy.