Fertility Blog

Revisions to Guidelines for Embryo Transfers

PFC has been a pioneer in enabling patients to have just a single embryo transferred at a time, through the use of genetic testing and freezing of embryos for later use. At PFC we elect to transfer one embryo in over 90% of patients and our twin rate is 6%. Nationally, clinics perform elective single embryo transfer in less than 30% of patients. North America has consistently had the highest multiple pregnancy rates in the world but this is changing and should continue to change with the new guidelines for number of embryos to transfer.

Datasets for eSET. Here’s one example: National data from 2013 showed that clinics performing more elective single-embryo transfers (eSETs) in women younger than 38 have lower rates of multiple pregnancies—but without sacrificing birth rates.1 And, in women 42 or younger, the transfer of a single euploid blastocyst (a 5- to 6-day-old embryo with the correct number of chromosomes) greatly reduces the risk of twins, while leading to pregnancy rates similar to those after the transfer of two genetically untested blastocysts.2

Multiple gestation—reality and risks. But the reality is that multiple gestations have continued to play too big a part in the assisted reproductive technology (ART) picture—even though they’ve begun to diminish.3 For example, nearly a quarter of women under age 38 with a successful in vitro fertilization (IVF) cycle in 2014 had a twin pregnancy.4 And nearly half of all multiple pregnancies resulting from ART in this country occur in women under age 35 who have had 2 fresh or frozen embryos transferred.5

This is not a good-news story. Multiples increase the risk of potential complications for both mother and child, including preterm delivery, low birth weight, gestational diabetes, and cesarean delivery.6

Guidelines for patients with a good prognosis. For reasons like these, the American Society for Reproductive Medicine (ASRM) and Society for Assisted Reproductive Technology (SART) recently changed their guidelines regarding the number of embryos to transfer during IVF cycles.3

To help reduce the number of multiple pregnancies and to promote the birth of one baby at a time, ASRM and SART now recommend limiting the transfer of euploid embryos to 1 in patients of any age who have a favorable prognosis. In addition:

  1. Patients under the age of 35 are encouraged to try eSET.
  2. Patients between ages 35 and 37 should strongly consider eSET.
  3. Patients between ages 38 and 40 should receive no more than 3 cleavage-stage (early-stage) embryos or 2 blastocysts. If euploid embryos are available, a single-blastocyst embryo transfer should be the standard practice, and is our practice at PFC.
  4. Patients who are ages 41 or 42 should plan to receive no more than 4 cleavage-stage embryos or 3 blastocysts. In cases where euploid embryos are available, a single-blastocyst transfer should be the standard practice, and is our practice at PFC.
  5. Patients who are 43 or older who are using their own eggs are advised to exercise caution when transferring more than 1 embryo. That’s because the risk of multiples increases with age.

Other guidelines. In consultation with their physicians, patients with a favorable prognosis who do not conceive after several cycles with high-quality embryos may consider transferring an additional embryo. Depending upon individual circumstances, patients who do not have a favorable prognosis may transfer an extra embryo after consultation about the risks involved.

Special cases. Patients who have a condition that may worsen significantly with a multiple pregnancy should limit the transfer of embryos to 1. For women using donor eggs, the age of the donor determines the appropriate number of embryos to transfer. At PFC, since all anonymous donors are in their 20’s we strongly encourage single embryo transfer. In women using frozen eggs, consider the age when the embryos were frozen as well as the presence of high-quality vitrified embryos, euploid embryos, first frozen embryo transfer (FET) cycle, or previous live birth after an IVF cycle. The numbers to transfer should not exceed the limits for fresh embryos recommended for each age group.

Individual programs. ASRM and SART also recommend that individual programs finesse their practices based on their own data about patients and numbers of embryos transferred. The goal is to maintain high pregnancy rates and limit multiple gestations, which means working to reduce the number of embryos transferred but not using data to exceed the recommended limits.

Accumulating this kind of data is exactly what encouraged us at Pacific Fertility Center to increasingly transfer a single embryo, even in many women over the age of 40. We’re proud to say that we’ve been at the cutting edge of the eSET revolution for several years, always making it our mission to help deliver one healthy baby at a time. PFC is way ahead of these guidelines and we transfer one embryo in over 90% of patients

Sources

  1. Mancuso A et al. Fertil Steril. 2016;106:1107–1114.
  2. Forman EJ et al. Fertil Steril. 2013;100:100–107.
  3. Practice Committee of the American Society for Reproductive Medicine, and the Practice Committee of the Society for Assisted Reproductive Technology. Fertil Steril.2017;107:901–903.
  4. Society for Assisted Reproductive Technology (SART). National Summary Report. Available at: [https://www.sartcorsonline.com/rptCSR\_PublicMultYear.aspx?ClinicPKID1/40. Accessed 1-12-17](https://www.sartcorsonline.com/rptCSR_PublicMultYear.aspx?ClinicPKID1/40. Accessed 1-12-17).
  5. Kissen DM et al. Fertil Steril. 2015;103:954–61.
  6. American Pregnancy Association: “Complications in a Multiple Pregnancy.” Available at: http://americanpregnancy.org/multiples/complications/#. Accessed 4-20-17.

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