Gynaecology & Obstetrics General 2a5a9879 Which of the following is true regarding chorionicity in multifetal pregnancy A Monochorionic membranes should have four layers B Dichorionic pregnancies are always dizygotic C Monochorionic pregnancies are always dizygotic D Chorionicity is accurately determined by first trimester ultrasound scan High-Yield Explanation Monochorionic pregnancies have dividing membrane that is 2 layer thick. Monozygous twins can be dichorionic as well.