raising twins,momo twins,monoamniotic,premature,identical,multiples The good, bad & the ugly...real life!: Monoamniotic Twins

Wednesday, February 9, 2011

Monoamniotic Twins

The simple definition:  Both babies are in the same sack and share a placenta.  They are very high risk and we were told only occur in .01% of twin pregnancies.
Another random fact regarding this type of pregnancy: 75% of them are girls.

When it was discovered that our twins are monoamniotic (also called momo) I was sent to a maternal fetal medicine specialist.  At the first appointment the dr. went on and on for at least two hours while drawing a diagram and explaining all of the risks of this type of twins.  He made very sure that I was aware that the survival rate was less than 50% and IF and only IF both babies were to survive the chances of them having severe brain damage and being blind  and/or deaf was close to 90%.  Needless to say, by the time I left the appointment in my mind I had buried my babies.  He suggested that I bring my husband back, where he went on to explain the same to him for three hours this time.  Yes, there are more risks and tragedies with monoamniotic twins but there are also risks and complications with "normal", single births.  Most frequently the complications are from strangling each other with the umbilical cords while in the womb.
I am including this post just in case there anyone reading this is in the same boat that I was in a few short years ago, hoping that you will see that there is hope.   We were very fortunate and I have heard of many others that have been as fortunate and some even more than we were.  I was hospitalized at 25 weeks and my babies were delivered at 28 weeks.  Baby A, Nicholas received a blood transfusion and has had some challenges with his lungs.  He had pneumonia several times and was diagnosed with Asthma.  Less than three years later he has outgrown most of his pulmonary issues.  He hasn't had pneumonia for over a year and we have not had to use his inhaler or nebulizer for almost a year!  Baby B, Hudson has a slight cerebral hemmorage and has had some developmental delays.  He is almost three and still not walking, but getting close and all of the specialists and therapists that care for him are confident that he will be where he should be or close to it by the time he starts kindergarten.  I have heard of several cases of monoamniotic twins that were delivered at 32-34 weeks that have spent some time in the NICU and been just fine.

Various types of chorionicity and amniosity (how the baby's sac looks) in monozygotic (one egg/identical) twins as a result of when the fertilized egg divides
Monoamniotic twins are identical twins that share same amniotic sac within their mother’s uterus.[1] Monoamniotic twins are always identical, and always monochorionic as well (sharing the same placenta), and are sometimes termed Monoamniotic-Monochorionic ("MoMo") twins.[1] They also share the placenta, but have two separate umbilical cords. Monozygotic twins develop when an embryo does not split until after formation of the amniotic sac,[1] at about 9 days after fertilization.[2] Monoamniotic triplets or other monoamniotic multiples[3] are also possible, but extremely rare.[1]


Monoamniotic twins are rare, with an occurrence of 1 in 35,000 to 1 in 60,000 pregnancies,[1] corresponding to about 1% of twin pregnancies.[3]


The survival rate for monoamniotic twins has been shown to be as high as 81%[4] to 95%[5] in 2009, although is often reported as being between 50%[1] to 60%.[3]. Causes of mortality and morbidity include:
  • Cord entanglement: The close proximity and absence of amniotic membrane separating the two umbilical cords makes it particularly easy for the twins to become entangled in each other’s cords, hindering fetal movement and development.[3] Additionally, entanglement may cause one twin to become stuck in the birth canal during labor and expulsion.[1] Cord entanglement happens to some degree in almost every monoamniotic pregnancy.[1]
  • Cord compression: One twin may compress the other’s umbilical cord, potentially stopping the flow of nutrients and blood and resulting in fetal death.[1] [3]
  • Twin-to-twin transfusion syndrome (TTTS): One twin receives the majority of the nourishment, causing the other twin to become undernourished. TTTS is much more difficult to diagnose in monoamniotic twins than diamniotic ones, since the standard method otherwise is to compare the fluid in the sacs. Rather, TTTS diagnosis in monoamniotic twins relies on comparing the physical development of the twins.[1]


Ultrasound is the only way to detect MoMo twins before birth.[3] It can show the lack of a membrane between the twins after a couple of weeks' gestation, when the membrane would be visible if present.[3]
Further ultrasounds with high resolution doppler imaging and non-stress tests help to assess the situation and identify potential cord problems.[3]
There is a correlation between having a single yolk sac and having a single amniotic sac.[1] However, it is difficult to detect the number of yolk sacs, because the yolk sac disappears during embryogenesis.[1]
Cord entanglement and compression generally progress slowly, allowing parents and medical caregivers to make decisions carefully.[3]


Only a few treatments can give any improvements.
Sulindac has been used experimentally in some monoamniotic twins, lowering the amount of amniotic fluid and thereby inhibiting fetal movement. This is believed to lower the risk of cord entanglement and compression. However, the potential side effects of the drug have been insufficiently investigated.[1] [3]
Regular and aggressive fetal monitoring is recommended for cases of monoamniotic twins. Fetal heart rate and movement is monitored twice-weekly, particularly after the 26th week. After the 28th week, many women enter inpatient care, with continuous monitoring,[1] preferably in the care of a perinatologist, an obstetrician that specialises in high risk pregnancies.[3]
All monoamniotic twins are delivered prematurely by cesarean section, since the risk of cord entanglement and/or cord compression becomes too great in the third trimester. The cesarean is usually performed at 32, 34 or 36 weeks.[3] Many monoamniotic twins experience life-threatening complications as early as 26 weeks, motivating immediate delivery. However, delivery around 26 weeks is associated with life-threatening complications of preterm birth.[1] Steroids may be administered to stimulate the babies' lung development[3] and decrease the risk of infant respiratory distress syndrome. Natural birth rather than cesarean section causes cord prolapse, with the first baby delivered pulling the placenta shared with the baby being left inside.


  1. ^ a b c d e f g h i j k l m n o Pregnancy-Info -- > Monoamniotic Twins Retrieved on July 9, 2009
  2. ^ Shulman, Lee S.; Vugt, John M. G. van (2006). Prenatal medicine. Washington, DC: Taylor & Francis. pp. Page 447. ISBN 0-8247-2844-0. 
  3. ^ a b c d e f g h i j k l m MoMo Twins; Monochorionic Monoamniotic Twins By Pamela Prindle Fierro, About.com. Retrieved on July 9, 2009
  4. ^ Hack KE, Derks JB, Schaap AH, Lopriore E, Elias SG, Arabin B, et al. Perinatal Outcome of Monoamniotic Twin Pregnancies. Obstet Gynecol. 2009;113(2, Part 1):353-60 http://journals.lww.com/greenjournal/Abstract/2009/02000/Perinatal_Outcome_of_Monoamniotic_Twin_Pregnancies.17.aspx
  5. ^ Baxi LV, Walsh CA. Monoamniotic twins in contemporary practice: a single-center study of perinatal outcomes. The Journal of Maternal-Fetal & Neonatal Medicine. 2009. http://www.informaworld.com/openurl?genre=article&issn=1476%2d7058&issue=preprint&spage=1&doi=10%2e1080%2f14767050903214590&date=2009&atitle=Monoamniotic%20twins%20in%20contemporary%20practice%3a%20a%20single%2dcenter%20study%20of%20perinatal%20outcomes&aulast=Baxi&aufirst=Laxmi&auinit=V%2e


  1. You are so tough to have handled all this. I think I wouldn't have had a tear-free day facing what you did. You are awesome!

  2. I am going through the same thing with the doctors they really know how to make you aware of the risks. I am 20 weeks and a day and carrying monochorionic monoamniotic twins and well i cope by leaving it in gods hands. You are a strong mother and your babies are perfectly fine. I wish you the best and thank you for sharing your wonderful story. It really uplifted my spirits with pregnancy of a successful delivery.