If you’re familiar with my personal fertility journey, then you know I had twins (via egg donor and IVF) at age 43. While the chances of spontaneously conceiving twins is quite low, advancements in assisted reproductive technology (ART) and the use of multiple embryo transfers has led to increasing numbers of twins and higher order multiples over time. I am an example.
In recent years, though, it has become more common to do single embryo transfers (SET) in order to reduce the risks of adverse pregnancy outcomes (APO) seen with multiple gestations. For some patients, doing a multiple embryo transfer might sound like the better option. It seems like it would give a higher chance of success with one or more embryos implanting, and the “one and done” twin pregnancy is appealing to some. However, there is not a higher success rate attached with transferring more than one embryo, and in some instances, transferring more than one embryo can reduce the success rate. In addition, the risks associated with a multiple gestation should be considered.
The American Society for Reproductive Medicine recommends a SET in order to reduce maternal and fetal risks, but they also do not discount the fact that for some individuals it might be worth the potential risks to transfer 2 embryos during an IVF cycle. For example, I had experienced 2 failed embryo transfers and a miscarriage. When I made the decision with my REI specialist to move forward with a 2-embryo transfer, I was counseled to ensure that I understood the risk to both myself and my pregnancy. Just as with any medical procedure, a patient’s medical history is taken into consideration before moving forward with a decision. My age, medical history and previous IVF history were taken into consideration before moving forward with a 2-embryo transfer. I delivered my twins prematurely at 31 weeks after a 2-month hospital stay due to complications.
In fact, you can hear more about my story in this conversation with Neonatologist, Dr. Michael Narvey (@nicu_musings on Instagram). We discuss SET, in addition to types of twins, twin-twin transfusion syndrome, laser therapy, ultrasound assessments, potential outcomes with preterm delivery, shared decision making, when to deliver if a twin pregnancy is complicated, and vanishing twins.
According to Dr. Karen Fox, “People with twin pregnancies have increased risks in general compared to people carrying a single fetus. In particular, twin pregnancies are at increased risk for preterm birth. On average, people with twins deliver around 36 weeks of pregnancy. This is mostly due to spontaneous preterm labor, which is defined as contractions and cervical change before term, or at less than 37 weeks of pregnancy. Other complications, such as preeclampsia or gestational diabetes, both of which are more common with twins pregnancies, can occur as well. These risks are increased even further with triplets, quadruplets or higher.”
A recent study in JAMA looked at the absolute risk of adverse obstetric outcomes with IVF and a singleton or twin pregnancy and maternal age. They found that twin pregnancy, IVF, and advanced maternal age were independently associated with adverse obstetric outcomes, and endorsed elective single embryo transfer strategy in order to reduce multiple pregnancies following IVF.
Among IVF-conceived twin pregnancies, the most common obstetric risks were:
Dr. Karen Fox shared on the Babies After 35 blog, “The difference between “identical” and “fraternal” twins often comes to mind, but from the obstetrician’s point of view things are a little more complex. First, let’s consider “identical” twins or twins that look exactly alike. In medical terms, we call these twins “monozygotic”, meaning the twins started out as a single fertilized egg that split into two embryos/fetuses that have essentially the same genetic makeup. On the other hand, fraternal twins are “dizygotic”, meaning they formed from two separate fertilized eggs and developed into two embryos/fetuses with their own unique genetic makeup.”
Because IVF is talked about more widely now, you might see or hear about someone using IVF to be able to select the sex of their baby or to electively have twins. What you cannot know, even if they share certain facts, is their entire medical history leading up to the decision made by the individual with their physician(s). You don’t know how many failed rounds of IVF they might have had, if there was an egg or sperm donor used, or any other information that would be used to make these decisions.
If you are considering IVF for any reason, seek out the counsel of an REI specialist as soon as possible. As I’ve shared before, do it for no other reason than to get the information and understand what IVF entails. Conceiving through IVF does not automatically mean you will have twins nor does it ensure a successful pregnancy. It is one option to help you in your fertility journey should you need it.
Shannon M. Clark, MD, MMS is a double board certified ObGyn and Maternal-Fetal Medicine Specialist, and founder of Babies After 35. In her roles as a clinician, educator and researcher at UTMB-Galveston, she focuses on the care of people with maternal and/or fetal complications of pregnancy. Dr. Clark has taken a special interest in pregnancy after the age of 35, which according to age alone, is considered a high-risk pregnancy.
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