Smart technology automatically groups people (who are “friends”) together according to what they have in common on their posts or about pages. This shows up on the right hand side of your Facebook newsfeed under “friends.”
While some light research shows, these lists are private to you and those you add to those lists, I would highly recommend that you do not add people that are in secure areas to that list. Better to err on the side of caution.
Instead, you can create a “secret” group to have your friends listed there to make sure communication is kept out of your other friends’ newsfeeds. Any other group designation, like “closed” or “private,” do not give you that same safeguard. Both of those latter designations actually will show up in your friends newsfeeds and public searches.
Friend A could post in those groups about her pregnancy and all 2,000 of her closest friends would see that in their newsfeed unless the group settings are on “secret.” For those extra-sensitive things, communicate them via email.
As with anything online, always be prepared in case you are “overheard” online (i.e. the cat is let out of the bag on purpose or by accident). Have a Plan B. Even snail mail in foreign countries can be read. Email in closed countries are monitored by the government. Create a code or designate someone to get those emails on your behalf.