Should I transfer one or two embryos?

A woman with a three-year-old daughter is contemplating IVF for a second, and is concerned about the statistics from her doctor about the chance for having multiples. Her clinic is closed the entire Christmas week, when she expects to ovulate next, and thus far they haven’t had any luck with insemination timing, so she is contemplating IVF – which she has to pay out of pocket. She feels financially she has one good shot for the costly IVF procedure. Her question – not at all uncommon for women on this journey — should she transfer one or two embryos? She is over the age of 40, which makes a difference.

And because she already has a daughter, she is very concerned about the chances of conceiving multiples.


Fertility Doctor Insight

I checked with Dr. Bill Baird of Columbus, Ohio-based Reproductive Diagnostics fertility services and Cryobiology sperm bank. I first met Dr. Baird years ago when I was asked to speak at the AATB (tissue banks) conference about the rights of donor-conceived children and donor identity issues. He impressed me then — and again recently at the 2013 AATB conference — as someone with integrity who speaks his mind and cares about the education of patients.

So I asked him: what is the prevailing research about single versus multiple transfer of embryos? He confirmed what I’ve been hearing in the industry, including at the 2013 ASRM conference (reproductive medicine):

If a clinic feels secure in being able to detect a quality embryo – ideally in blastocyst stage — for transfer, transferring ONE high-quality embryo should not dramatically diminish the chances of pregnancy yet will significantly reduce the likelihood of twin births.

In his practice, he said, there were 57 single embryo transfers during the past year; 35 resulted in a pregnancy, which is a good 65 percent success rate (because yes, even with embryos implanted with lab assistance, success is not guaranteed). Of those 35 pregnancies, one resulted in a naturally occurring incidence of multiples (because, yes, accidental twinning can occur as well).

As reported in a 2013 publication created from a roundtable discussion of experts about this topic, “Redefining Success in IVF: Reducing the Burden of Care”When using stimulated ovulation and assisted reproductive technology, the incidence of twins is more than 20 times greater than that of naturally conceived twins. This is generally not considered a great thing, even for married couples, because of the risks for preterm birth complications and post-delivery health issues. Following is some of the data they collected and reported.

Age Groupunder 3535-3738-4042over 42
Number of cycles39,72119,93020,13010,2776,033
Average number of embryos transferred1.92.12.53.03.1
Percentage of cycles with elective single embryo transfer11.7%6.5%1.9%.6%.5%
Percentage of live births with twins30.8%26.7%21.1%14.9%10.6%


Research Says

At the 2013 ASRM conference, I also learned about a few recent studies related to embryo transfer, timing, and IVF success rates.

Thanks to advances in cell culture techniques, high-quality clinics are able to improve embryo selection before transfer, resulting in higher implantation rates.

A study by the Regional Fertility Program in Calgary, for example, analyzed 1304 embryo transfers, from patients younger than 37 who were not using egg donors. If two blastocysts of a grade below 3BB were transferred, the pregnancy rate was 66 percent with a 25 percent chance of twins.

The team determined that single embryo transfers in the study achieved equivalent pregnancy rates while significantly reducing the multiple pregnancy rate. Thus, it was recommended that one blastocyst with a grade of 3BB or better produces an acceptable pregnancy rate. “If patients do not have embryos with this minimum grade, consideration should be given to transferring two lower grade blastocysts in order to maintain an acceptable pregnancy rate but a greater number of twins may be conceived.”

A pilot study by the Virginia Center for Reproductive Medicine and George Washington University looked at the incidence of couples who were given incentives to transfer single embryos – yet still tended to choose multiple transfers. Despite counseling on the increased risks associated with twin pregnancies, it is thought that many who have struggled with fertility prefer to have two and thus declined single embryo transfer.

Statistically, 17 of the 24 women in the Virginia study who elected to use single embryo transfer were successful at conceiving (71 percent).


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