What do I say? (Trigger Warning⚠️)

I’m 22, pregnant and have decided on abortion. My boss is very very strict and I’m trying to avoid having to answer why I’m going to be out of work for a day. My workplace is very very family oriented and I’m almost positive they might fire me if I told them what’s really going on (ok maybe not, but I’m terrified). Any suggestions of what I can/should tell my boss?