By: Dr. Meaghan Bowling

One of the critical conversations that we have with our patients at Carolina Conceptions is the decision of how many embryos to transfer during an IVF cycle.  Often, infertility patients have experienced years of disappointment, with month after month of negative pregnancy tests and failed fertility treatments.  By the time they decide to do an IVF cycle, I often hear things like, “We wouldn’t mind twins at this point” or “How can we have twins”?

We understand how important it is for our patients to be pregnant as soon as possible, but with great advancements in IVF over the last few years, our chances of success with transferring one embryo at a time can yield the same high pregnancy rates that were previously seen with transfer of 2 or more embryos. 

Why is the infertility field moving towards eSET (Elective Single Embryo Transfer)?

Often patients are unaware of the risks of having twins or higher order multiples (triplets and beyond).  Twin pregnancies are high risk for both the mother and the twins.  These risks are increased in women over 35, as risks in pregnancy increase with age.  Women of any age with medical conditions such as high blood pressure, diabetes, and obesity are also at higher risk of pregnancy complications with a twin gestation.

What are the risks of a twin pregnancy in the mother?

Women who are pregnant with twins have higher chances of pre-eclampsia/eclampsia (high blood pressure, seizures in pregnancy), gestational diabetes, psychological issues in pregnancy, and higher rates of c-section compared to women who have a singleton pregnancy.

What are the risks to the twins?

Another major concern is the higher risk of preterm birth and low birth weight among twin pregnancies.  60% of twin pregnancies deliver preterm, and these babies are at risk for stays in the neonatal intensive care unit (NICU), and complications of prematurity including life-long problems like developmental delays, learning disabilities, and cerebral palsy.  And very sadly, a small percent of twins deliver so early (<24 weeks gestation) that they may not survive after birth.  These types of outcomes are heartbreaking no matter the circumstance, and certainly devastating after a battle with infertility.

How do twin pregnancies affect our country from a public health standpoint?

Twin pregnancies are a major public health concern.  One study found that the U.S. national healthcare cost was around $21,000 per delivery of a singleton vs. $105,000 for a twin delivery.  Preliminary data from a CDC study indicated that single embryo transfers could save a total of $1 billion annually in healthcare costs nationwide.  Some countries mandate single embryo transfers for their patients who are undergoing IVF.  In the United States, some insurance companies are starting to require single embryo transfer for patients with IVF coverage.

What criteria does ASRM (American Society of Reproductive Medicine) use to determine the number of embryos to transfer in each patient?

Carolina Conceptions follows ASRM guidelines on number of embryos to transfer.  These recommendations are based on a woman’s age, whether she has had genetic screening of her embryos, and whether she falls into the category of “favorable” prognosis or not.  A patient with a favorable prognosis is one who has 1) one or more high quality day 5 or 6 blastocysts from an IVF cycle, 2) embryos with normal genetic screening after PGS (preimplantation genetic screening), and 3) a previous live birth from an IVF cycle.

How do the new 2017 ASRM guidelines differ from the previous guidelines?

The first major change is the new recommendation that all women under the age of 38 with a favorable prognosis should transfer a single blastocyst, regardless of whether they have done preimplantation genetic screening (PGS) or not.  Women who are ages 38-40 who do not use PGS should transfer 1-2 embryos.

The second major change is the recommendation that all women who have IVF with PGS, regardless of their age, should transfer 1 embryo at a time.  This is based on studies showing that in women 42 years of age and younger, transferring a single genetically normal blastocyst results in pregnancy rates similar to transferring two untested blastocysts while dramatically reducing the risk of twins.

What is the bottom line?

The decision on how many embryos to transfer is an important discussion to have between the patient and their physician.  We take into consideration each patient’s individual infertility history and medical circumstances.  Our goal at Carolina Conceptions is to help each patient achieve a single healthy pregnancy, and help each woman have the healthiest pregnancy possible.

For more information on eSET, check out this CDC Website.


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