Apr 13, 2023 · The only types of twins you might be familiar with are identical and fraternal, but many twin types exist. Learn about mono/di twins, diagnosis, risks, and more.

What are monochorionic, diamniotic twins? Monochorionic, diamniotic (MCDA) twins are the product of a single fertilized ovum (egg), resulting in genetically identical offspring. MCDA …

Aug 11, 2023 · Mono di twins are identical twins who share the same placenta but have separate amniotic sacs. Learn the causes and risks of a mono di twin pregnancy.

Feb 11, 2025 · What is a mono-di twin pregnancy? A mono-di (or mo-di) twin pregnancy is one where twins share a placenta and each have their own amniotic sac. Mono-di is short for monochorionic diamniotic, meaning one chorion, two amnions. (The chorion is the outer membrane surrounding the embryo, and it develops into the placenta.

Everything you need to know about mono di twins, and what it means for you and your babies.

Monochorionic-diamniotic twins account for approximately 20% of spontaneous twins and approximately 4% of twins conceived by artificial reproductive techniques.

Monochorionic diamniotic (Mo-Di) twins are twins that share a placenta and therefore a blood supply. They occur in 3–4 per 1,000 pregnancies. They are not the type of twins that run in families. The only known risk factor is in vitro fertilization (IVF). About 4% of IVF pregnancies will have monochorionic twinning.

Mo-mo twins, also called mono-mono twins, share both a placenta and an amniotic sac. It’s the least common type of twin pregnancy, occurring in only 1 – 5% of twin pregnancies. And all mo-mo twins are identical. Di-di twins each have their own placenta and amniotic sac.

Monochorionic twins generally have two amniotic sacs (called Monochorionic-Diamniotic "MoDi"), but sometimes, in the case of monoamniotic twins (Monochorionic-Monoamniotic "MoMo"), they also share the same amniotic sac. Monoamniotic twins occur when the split takes place after the ninth day after fertilization. [2] .

Monochorionic diamniotic (mo/di) twins are identical twins that each have their own amniotic sac but share the same chorionic sac and the same placenta. The way in which the egg splits and the timing thereof determines whether identical twins will be mo/di, di/di, or mo/mo.