So, I was supposed to be a twin, but my twin was absorbed in the womb, which is known as "Vanishing Twin Syndrome", but i have a few questions about this - Lemmy.World

I’ve looked up Vanishing Twin Syndrome, and almost every article I have seen said that VTS typically only happens during the first trimester of the pregnancy. But here’s the catch: My mom didn’t realize or know she was pregnant with me until 7 months into the pregnancy. And when she found out, the ultrasounds did show two babies. Me and my twin? If Vanishing Twin Syndrome usually only occurs during the 1st trimester, is there a reason why it can happen so late during the pregnancy, as in the case with my mom and my twin?