However, after TTTS developed, the second trimester maternal serum sFlt1 and the sFlt1 to PlGF ratio were significantly increased in the MC twin pregnancies with TTTS compared with the uncomplicated MC twin pregnancies Interestingly, decreased PlGF without increased sFLT1 like in TTTS was observed in the first trimester in patients who developed PE [38]. Here, PGF is linked to twin to twin transfusion syndrome.