Winning the Genetic Lottery

From the start, our pregnancy was classified as high risk simply because we were carrying twins. Truthfully though, since the beginning of our pregnancy was so smooth, I really didn’t pay much attention to this label. Until one takes a quick glance at the statistics regarding twin or triplet pregnancies, it’s easy to forget just how delicate a multiple pregnancy can be.

Compared to singleton pregnancies (one baby), multiples are almost 17 times more likely to be born prematurely, with half of all twins having a birth weight under 5.5 lbs. And, as was such in our case, women carrying twins are twice as likely to experience a stillbirth.*

During the pregnancy, I was unconcerned about potential risks; I had seven pregnant months with absolutely no warning of what was to come. The medical staff kept telling us that it was “the perfect pregnancy.” During each ultrasound, the technicians were constantly amazed at just how well the boys and I were doing. At one appointment, as I hopped up onto an exam table, our obstetrician looked at me with surprise and said, “You’re carrying two better than most women carry one!”

At twelve weeks we were told that we had “won the genetic lottery” and were carrying identical twins. The doctors and hospital staff were excited to work with us, citing how rare it is to see a couple as young as ourselves naturally conceive identical twins. The chances of getting pregnant with identical twins is 1 in 250, less than 1%.

What are identical twins, you ask? Compared to fraternal twins which begins with two separate eggs, identical twins occur when a fertilized egg splits into two. This is why fraternal twins can be a boy and a girl, while identical twins have to be the same gender. Non-identical twins can be influenced by genetics but identical twins are considered “random.” (Sounds simple enough but you’d be amazed how many times I had to explain that during the pregnancy…)

Until we became pregnant with the boys, I always thought that twins were simply “identical” or “non-identical.” However, there are actually several different types of twins:

  1. Dichorionic diamniotic twins (also called di-di). These twins are the lowest risk. They each have their own placenta and their own amniotic sac. All fraternal twins and a third of identical twins are di-di.
  1. Monochorionic diamniotic twins (also called mono-di). These twins are a medium risk. They share a placenta but each have their own amniotic sac.
  1. Monoamniotic monochorionic (mo-mo twins). At a 50% mortality rate, these twins have the highest risk. They share a placenta and an amniotic sac putting them in danger of cord entanglement.

Our twins were mono-di meaning that we were at risk for “Twin to Twin Transfusion” (TTTS). This syndrome occurs when when a connection develops between the blood vessels of the babies’ shared placenta. One baby (the recipient) receives more blood while the other baby (the donor) receives too little. Early signs of TTTS can be seen on ultrasounds when one twin is significantly smaller than the other or there is a difference in size between the amniotic sacs.

TTTS only affects identical twin (or higher multiple) pregnancies. It’s estimated that ten to twenty percent (10 – 20%) of monochorionic twins develop twin to twin transfusion.

Because of this risk, we were booked for ultrasounds every two weeks to watch the growth of the twins. We were told that if a size discrepancy was noticed between the boys, the situation would be monitored by weekly or, if necessary, daily ultrasounds. However, this was never a problem. At each ultrasound, the technicians were surprised by how similar in size the boys were – only a couple grams difference. At one ultrasound, I was concerned that the technician had measured the same twin twice as they were the exact same size and weight.

Because we didn’t show signs of early twin to twin transfusion – the medical community didn’t seem to emphasize potential risks or warning signs. At 28 weeks, we went in to meet with one of our obstetricians and were told that we were most likely “out of the woods.” She informed us that, “If the twins haven’t shown signs of growth discrepancies by now then they probably won’t.”

The problem is that there are two types of Twin to Twin Transfusion: Chronic TTTS, which is usually spotted earlier in the pregnancy, and Acute TTTS, which can happen at any time – even during labour. There is no “safe” period. When an Acute Twin to Twin Transfusion occurs, it can happen extremely quickly.

On Saturday, July 19th we went in for one of our regular ultrasounds. Everything was perfect, no sign of anything wrong. Five days later, everything was wrong. There were no warnings; it was abrupt and confusing. A perfect pregnancy that wasn’t so perfect after all. I never imagined that it could ever end the way it did – but while I watched my world crumble, there was one who held it in His hands. One who was in control, who knew what He was doing. One who gave me a pregnancy full of memories, laughter and sparkling anticipation. One whom I can rely on in the sunshine and in the rain. And while we’ll never fully know the why, we do know that His plan is perfect. Through it all, He is good; He is faithful to His promises.

*Stats from http://www.multiplebirthscanada.org

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