It is caused by very high levels of hCG, which can be a result of: Multiple pregnancy (twins, triplets, or more) The pregnancy being further along than expected Molar pregnancy Levels of hCG need to ...

About 1 in 5 twin pregnancies are monochorionic ... these images are clearest before 14 weeks pregnant. The ideal point to identify which type of twins you're having is between 11 and 13 weeks ...