Twin Rabbit Hole

When I found out that we were having twins, I was told that I was about to be "thrown down a rabbit hole" of twins. Types of twins, complications of twins, twin mom facebook groups... I was warned but viciously unprepared for what twins mean as a whole besides, you know, two babies.

Mo-Di Twins

What does it mean to have Mo-Di twins? Mo-Di or Mono-Di or MCDA twins are Monochorionic diamniotic, meaning one chorion and two amnions. The easiest way to understand this is one placenta and two individual amniotic sacks. Mo-Di twins are (almost always) identical. Nature is weird, so there are always outliers and I have read about some cases of two eggs fusing together and then two embryos sharing a placenta. Again, science and nature are weird. Generally, one egg split into two embryos, these embryos each developed their own individual sacs.

What did this mean for me?

Besides realizing that I was going to need to buy at least one more of some very expensive baby products, ie: Nuna car seats, what did this mean for me and my pregnancy? It meant that I was going to feel like I was living at Mass General. I started every other week appointments at 16 weeks. Ultrasounds every visit, which made appointments feel like they went on forever. I had to have echocardiograms, of each baby, while in utero. I thought I wasn't going to make it through those appointments. Three HOURS of laying on my back for the scans.

Mo-Di twins meant that there was a seemingly endless list of what could go wrong. Sometimes it felt as if there wasn't a ton of positives being spoken about. I went into each appointment with the looming knowledge that if a scan didn't go well, I would need to go to either Childrens Hospital of Philadelphia or to Miami for surgery. Imagine? Living in Boston and being told that no doctor in BOSTON does this specialized surgery that you might need at a moments notice to keep your babies from dying?


Due to being Mo-Di twins, we faced a medical complication that is unique to only this type of pregnancy. Twin to Twin Transfusion Syndrome. TTTS occurs in about 10% of Mo-Di or higher multiples pregnancies. It is where the placenta isn't shared correctly. I'll spare you the details, but Boston Children's Hospital has wonderful information on the topic, just no in house treatment. We were also monitored closely for sIGUR, selective intrauterine growth restriction. Even as a former nurse, this was so over my head and overwhelming.

More about twins to come.