Monochorionic Monoaniotic (MoMo) Twins: Risks & Treatment


Many women want and aspire for twin pregnancy. If a woman is diagnosed with MoMo twins the pregnancy is a risky one. Simple facts and knowledge about the various risks involved can ensure that the mother-to-be understands what is happening and what is better.

momo twins

In this article:

What are Momo Twins?
Why Do they Form?
How are Mono-Mono Twins Diagnosed?
Risks and Complications Associated with Monochorionic Monoamniotic Twins
Treatment for Monoamniotic Twins
Other Facts About Mono Mono Twins

All You Need to Know about MoMo Twins

What are Momo Twins?

MoMo twins are monochorionic which means having single egg covering sac and monoamnioyic having single and same amniotic sac within their mother’s uterus. Both babies are in the same amniotic sac and have only one single covering egg sac or chorion. These twins are also known as mono mono identical twins and just about one percent of all twins are MoMo twins. These twins share the placenta but have two separate umbilical cords.The pregnancy is known as a high risk pregnancy.

Why Do they Form?

When the egg and sperm unite and become one, this process is called fertilisation (fusion of gametes). The resultant embryo is immediately covered with a chorion or egg sac to help and protect the developing embryo. Twins occur when there are two embryos in the uterus due to a split. In MoMo twins, the embryo during the process of growing, emerges as two separate embryos each developing a placenta that connects to the mother’s uterus. If each embryo develops its own amniotic sac, it is known as diamniotic and two embryos will share the same egg sac while advancing in their sacs. However, when only one amniotic sac is present, both embryos grow in a single amniotic sac and a single egg sac covering and which leads to momo twins.

How are Mono-Mono Twins Diagnosed?

Ultrasound scanning is the only one way to detect MoMo twins. High resolution ultrasound doppler waves are used to study the growing foetus in real time. This twin pregnancy needs aggressive monitoring and expert care of a perinatologist.

Risks and Complications Associated with Monochorionic Monoamniotic Twins

Most of the MoMo twin deliveries are premature deliveries. The twin foetuses connect to the placenta via the umbilical cords. There are following risk of several complications –

Cord Entanglement

it is a complication associated with monoamniotic twins sharing a single amniotic sac. Since there is no amniotic membrane separating them, the umbilical cords could get entangled, cutting off the vital blood supply and nourishment to the growing babies. If the twins get entangled and tied together in the uterus, labor and delivery may be complicated as one of them could get stuck in the birth canal. This can endanger the life of the babies and cause foetal distress.

Cord Compression

as twins share the amniotic sac, there is a chance that they might press against the others umbilical cord while making internal movements. Prolonged pressure may cut off the blood supply and nutrients from travelling to the other baby, resulting in foetal death.

Twin-to-Twin Transfusion Syndrome (TTTS)

this syndrome happens when one twin receives the majority of the nourishment in the womb, causing the other twin to become undernourished.

Preterm Birth

All monoamniotic twins are born prematurely because full-term pregnancy is at high risk and deemed unsafe due to the risk of cord entanglement, compression and other complications. Usually the twins are delivered by cesarean section after 34 weeks in the womb.

Many monoamniotic twins have to be delivered, sometimes as early as 26 weeks depending on the risks and complications involved. MoMo twins with a preterm delivery face many life-threatening conditions both in the womb and on being delivered.

Treatment for Monoamniotic Twins

High resolution Dopper Ultrasound imaging is used which is a non-stress test will help assess the growth and identify potential cord problems. These tests allow the doctor to study if it is necessary to intervene or deliver babies, due to their cords getting entangled or compressed.

The process of MoMo pregnancy is considered high risk, so there is no other way to deliver the babies in cases of complications. A perinatologist should be consulted to weigh the risks of the pregnancy or whether there is any threat to the lives of the mother and babies.

Usually these twins are delivered after 32 weeks and steroids administered to help their lung development after birth. A cesarean section is done for MoMo babies to avoid cord prolapse, which occurs when the second baby’s cord is expelled as the first baby is delivered.

A recent experimental drug, Sulindac has been used to lower the amount of fluid in the amniotic sac. This reduces the amount of foetal movement, cord entanglement and compression.

Aggressive foetal monitoring of the monoamniotic twins is a must throughout the pregnancy with bi-weekly control of foetal heart rate and movement after the 26th week. It is advised to hospitalise after the 28th week.

Other Facts About Mono Mono Twins

  • These babies are always the same sex babies since the splitting of the same embryo forms them.
  • These twins are very rare, only 1 percent of twins are monoamniotic.
  • In early pregnancy and up to 24 weeks, the monochorionic twins have a low survival rate of almost 50%.
  • A drug Sulindac that lowers the amount of amniotic fluid, thereby reducing the space that babies have to move around. The use of this drug needs further research and should be used with caution.
  • If there is MoMo multiples, try going to a perinatologist rather that the regular obstetrician. This is because MoMo twins are classified as ‘high-risk’ and would require a specialist doctor of such pregnancies.
  • After 28 weeks of pregnancy, hospitalisation is advisable.
  • In early pregnancy, MoMo twins are sometimes misdiagnosed because the separating amniotic membrane is fragile. Later ultrasound scanning reports could reveal a dividing membrane confirming a monochorionci, diamniotic (MoDi) pregnancy.


Monochorionic monoamniotic is a rare and high risk case of twins. They have complications but can be treated. They have risk for cord entanglement, congenital malformations, TTS and prematurity. Better to consult a perinatologist for safe delivery.