Low level antibodies

Sarah • 💙 Owen Thomas 💙
I'm 26+3 and just received a call from my doctor saying a very low level  unidentified antibody was found in my bloodwork. I had this show up before at around 13 weeks, they checked for it the following month and it was gone. Now that it's back it freaks me out! He's never concerned, just keeps checking for it. Has anyone else had this happen during their pregnancy? I'm really wanting to know what's causing it and why it's back.