Many couples request their doctors for transferring two embryos in IVF but does it really help?
If you too are keen on taking a chance on twins in IVF with two embryos, it is imperative that you weigh the risks and benefits of double embryo transfer (DET) after a detailed discussion with your doctor ahead of the procedure.
Traditionally, DET was done to improve the odds of implantation, but it was found to increase the risk of various neonatal complications.
According to a CDC report, the NICU admission for babies born from single embryo transfer is significantly lower as compared to those born from DET. One out of every 10 women with twin babies are more likely to have preeclampsia, high blood pressure, and other health complications (1).
What happens when two embryos are transferred?
During a typical IVF cycle, multiple mature eggs are retrieved from the ovaries and fertilized in the lab. If everything goes well, you should have several good-quality embryos from this.
On day 3 (cleavage stage) or day 5 (blastocyst stage) of fertilization, one or more high-quality embryos are then delicately placed inside your endometrial cavity.
The chances of having a healthy baby with the number of embryos per IVF cycle are explained through this chart (2):
| Embryo stage/ Day of transfer | Single embryo transfer(fresh) | SET (fresh) followed by 1 SET (frozen) | Double embryo transfer (fresh) |
|---|---|---|---|
| Cleavage stage (2-3 days) | At least one baby – 38% Twins – <1% | At least one baby – 55% Twins – <1% | One baby – 49% Twins – 16% |
| Blastocyst stage (5-7 days) | At least one baby – 51% Twins – <1% | At least one baby – 66% Twins – 1% | One baby – 60% Twins – 27% |
The above data indicates that transferring one fresh embryo followed by one frozen embryo has the best embryo outcomes without raising the risk of twins.
A different analysis also found that the transfer of two good-quality blastocysts provided a higher clinical pregnancy and live birth rates as compared to the transfer of a single embryo, but the multiple pregnancy rate was also higher (3).
Pros and cons of transferring two embryos in IVF
This decision should be made with your doctor after you consider these pros and cons of transferring two embryos:
Pros
- Raises your chances of pregnancy
- Saves both time and money
- Can have twins, if you want
Cons
- Risk of labor complications (such as labor and delivery bleeding and less than 29 weeks of gestation period)
- Risk of gestational diabetes and pre-eclampsia (high blood pressure, high levels of proteins in urine, or other signs of organ damage)
- Higher infant mortality rate
- Possibility of cerebral palsy in babies
- Children born with low birth weight or those born prematurely can suffer from both cognitive and emotional issues later in life
Can I try for twins in IVF with two embryo transfer?
If you are tempted by the idea of having twins via IVF DET, you might want to have a detailed discussion with your doctor in advance.
By 2011, about 36% of twin births and 77% of triplet births in the US resulted from assisted fertility treatments (4) but given the risks, many doctors are now advocating for single transfer in IVF.
Sometimes the concept of ‘vanishing twins’ may be applied to increase the chances of a successful pregnancy. In a study of 4,640 IVF cycles, it was shown that transferring a good-quality blastocyst along with a poor one confers no advantage (5). On the other hand, if any of the embryos you choose to transfer are chromosomally abnormal, it may also have an adverse effect on the other healthy embryo.
Vanishing twin survivors have an elevated risk of preterm birth and low birth weight compared to singletons from a single gestation as seen in an analysis of 709 multiple and 5962 singleton pregnancies (6). In comparison, if both embryos are of poor quality, you may have a higher chance of positive pregnancy.
In an approach called the Mixed Double Embryo Transfer (MDET), two embryos at different developmental stages – Day 3 (cleavage stage) and Day 5 (one blastocyst) stage are transferred together in a single unstimulated cycle. The technique is usually applied to patients with repeated implantation failure or those who wish to have twins. Frozen embryos are used for this purpose.
While any pregnancy has risks, the chances of healthy twins or triplets with IVF are relatively lower in a single transfer. So, if you wish to avoid dizygotic twins, opt for a single embryo transfer at a time.
Double embryo transfer success stories
Over the past decade, more fertility specialists have recommended SETs for safer outcomes. However, not all stories are equal. Celine Dion’s second pregnancy story is one of the most inspiring double embryo transfer success stories that we know.
After having her first child René-Charles in 2001 through IVF, she planned for a second pregnancy. After 6 failed IVF attempts, she was finally pregnant with fraternal twins at the age of 42 in 2010.
The similar IVF story of Nita and Mukesh Ambani (one of the top ten of the world’s richest) resulted in the birth of their twins Isha and Akash Ambani after 8 years of marriage. Neeta also conceived her third son Anant Ambani naturally after 3 years of her first pregnancy.
Single vs. Double embryo transfer success rate
The success rate of an embryo transfer has much to do with embryo quality rather than quantity. In a comparison of SET vs DET in IVF-PGT cycles of 611 patients between January 2017 to February 2021, the following observations were noted (7):
| Double embryo transfer | Single embryo transfer | |
|---|---|---|
| Live birth | 64.2% (with 35.3% twin gestations) | 81.9% (with a 98.5% singleton rate) |
| Reasons for no live birth | 27.5% biochemical loss, 18.5% clinical loss, and 53.9% not pregnant | 21.5% biochemical loss, 23.7% clinical loss, and 54.8% not pregnant |
In general, younger women or those who haven’t faced failed IVF earlier may opt for either single or multiple embryo transfers, but women their late 30s or 40s are advised for single embryo transfer to reduce strain on the uterus and the placenta and improve their chances of having a healthy baby.
According to recent trends, if you have more than one good-quality embryo, it is now considered best to implant one embryo at a time and freeze the others. In a 2020 study published in the British Medical Journal, it was found that 2 frozen embryo transfer success rates (or the freeze-all strategy) were similar to a fresh transfer strategy (8).
How many embryos to transfer in IVF?
The American Society for Reproductive Medicine recommends the transfer of a single euploid blastocyst in women less than 35 years of age, for the best outcome in their first IVF cycle (9).
If the embryos are relatively poorer in quality as judged by the embryo grading chart, or if the woman is of advanced age or has had several failed IVF cycles, the doctor may consider two or even three embryos for the best chances of success.
If you wish to consult an IVF expert on transferring two embryos in IVF, get in touch using the red message button here.
References
- CDC: Having healthy babies one at a time (Handout 2) https://www.cdc.gov/art/pdf/patient-resources/Having-Healthy-Babies-handout-2_508tagged.pdf
- CDC: Having healthy babies one at a time (Handout 1). https://www.cdc.gov/art/pdf/patient-resources/Having-Healthy-Babies-handout-1_508tagged.pdf
- Park D.S, Kim J.W, Chang E.M, Lee W.S, Yoon T.K, Lyu S.W. Strategies in the transfer of varying grades of vitrified-warmed blastocysts in women aged over 35 years: A propensity-matched analysis. J Obstet Gynaecol Res. 2019; 45: 849-857. DOI: 10.1111/jog.13897
- Aniket D Kulkarni, Denise J Jamieson, Howard W Jones Jr, Dmitry M Kissin, Maria F Gallo, Maurizio Macaluso, Eli Y Adashi. Fertility treatments and multiple births in the United States. DOI: 10.1056/NEJMoa1301467
- Micah J Hill, Allison E Eubanks, John M Csokmay, Alicia Y Christy, Samad Jahandideh, Alan H DeCherney, Kate Devine, Eric D Levens, Matthew T Connell. Is transferring a lower-quality embryo with a good-quality blastocyst detrimental to the likelihood of live birth? 2020 Aug;114(2):338-345. DOI: 10.1016/j.fertnstert.2020.03.027
- Dickey RP, Taylor SN, Lu PY, Sartor BM, Storment JM, Rye PH, Pelletier WD, Zender JL and Matulich EM (2002) Spontaneous reduction of multiple pregnancy: incidence and effect on outcome. Am J Obstet Gynecol 186,77–83. DOI: 10.1067/mob.2002.118915
- J Rodriguez-Purata, M Roque, R Colabianchi, M Colabianchi, E Cervantes-Bravo. -779 Single (SET) versus double embryo transfer (DET) in PGT-A cycles: cumulative live birth rates (CLBR) and multiple pregnancy rates using a Markov decision-analytic model. Human Reproduction, Volume 37, Issue Supplement 1, July 2022, deac107.719. 30th June 2022. DOI: https://doi.org/10.1093/humrep/deac107.719
- Sacha Stormlund, Negjyp Sopa, Anne Zedeler, Jeanette Bogstad, Lisbeth Prætorius, Henriette Svarre Nielsen, Margaretha Laczna Kitlinski, Sven O Skouby, et al. Freeze-all versus fresh blastocyst transfer strategy during in vitro fertilization in women with regular menstrual cycles: multicentre randomized controlled trial. 5th August 2020. BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m2519
- American Society for Reproductive Medicine guidelines for a number of embryos (fresh or frozen) to transfer. https://www.fertstert.org/article/S0015-0282(09)03625-5/pdf
