Some Basic Background Information

Before I actually start to officially "blog" about my exciting adventures here at VGH, I'd like to quickly explain what momo twins are.  Mostly because people ask me all the time, and I try to explain (obviously not in great detail), but I get the feeling they still don't understand.  Also because I didn't know anything about momo twins until I became one of the lucky mom's to carry them.

"Momo" is short for "mono amniotic mono chorionic".  Momo's are also called mono-mono twins.  Mono, standing for one; one amniotic sac, one placenta.  Therefore, momo twins share one sac and one placenta.  This makes them identical.  Other identical twins (mono/di - mono chorionic di amniotic - one placenta, two sacs) can only be determined through DNA testing of the twins themselves after birth because two placentas can sometimes fuse together and look like one at delivery.  Believe it or not,  Mary-Kate and Ashley Olsen are not identical twins, they're fraternal - fraternal meaning two placenta's, two amniotic sacs or di/di - di amniotic di chorionic. This is when two eggs get fertilized at the same time with two seperate sperm.  Essentially they are just like any other siblings, except they share a birthday.  With identicals though, one egg gets fertilized and then splits into two, establishing identical DNA. 

Sorry, a little of track there, so back to momo's.  With momo's, the embryo splits between day 8 and 13 after fertilization, meaning that an amniotic sac has already had plenty of time to form and the result is two embryo's in a single sac.  Usually with identicals, the embryo splits between day 4 and 8, then the sacs form, resulting in each embryo being housed in their own sac - the most common type of identical twins.  If an egg splits between days 13 to 15 after fertilization, the result is conjoined twins.  Having said that, we are pretty lucky to not have had that result.

Now for some statistics about momo's.  Momo's occur in about 1 in 35,000 to 1 in 60,000 pregnancies (or 1% of all twin pregnancies).  That makes them extremely rare. (Yay, us!)  The survival rate for momo's is about 50%  without agressive fetal monitoring.  When monitored, these statistics rise drastically to a more hopeful outcome of 80-90%.  If patients are fortunate enough, they are offered inpatient care after viablity (25 weeks gestation).  Generally, babies born before 25 weeks do not have a good chance of survival, and if they do, they do not do well.  

Once inpatient, patients are monitored multiple times throughout the day in the form of a non-stress test (NST) with auscultation (listening to the hearbeats) several times throughout the day.  The reason behind this agressive fetal monitoring is to catch any complications that may arise. These complications can be either TTTS (twin-to-twin transfusion - where one twin receives more nourishment than the other resulting in different growth patterns and malnourishment of one twin), cord compression and cord entanglement.  Cord entanglement is inevitable in momo's. Since they have skin-to-skin contact and are able to swim around each other (because there is no membrane dividing them) their cords become easily tangled.  This is fine as long as they don't pull tight and compress.  Cord compression happens when one twin compresses the cord of the other, or when one of the knots pull tight, stopping the flow of oxygen and nutrients.  Cord entanglement and cord compression are the most cause for concern in momo's.  With the inpatient monitoring, chances of catching these complications are better than when patients are not being monitored at all.  If cord compression happens, the babies must be delivered (as there is nothing anyone can do) no matter what gestation they are (hence the offering of hospital care at the age of viability - 25 weeks). 

So, that all being said, I am one of the lucky ones to have been offered inpatient care (as are all Canadians).  And here I am, nearing 28 weeks (which is considered a huge milestone as the chances of them doing well and with no long term complications significantly improve from the 25 week mark).  Mom and babies are still going strong, the babies are healthy and growing right on target, and I have not gone completely crazy (yet).