It’s a question that comes up before almost every transfer. And that’s with good reason – there aren’t any hard-and-fast rules you can universally apply to IVF - each cycle is different, and each uterus that receives the embryos is different. There are so many variables to consider that are not only physical, but emotional as well.
The most basic guideline is that you should transfer only as many embryos as babies you are willing to carry to term – no more.
But even this seemingly logical advice might be simplifying things a little too much.
Only in a perfect world would one embryo transferred result in one baby being born, making the decision of how many embryos to put back in an easy one. But as we know, not every embryo transferred grows into a baby, and on the flip side, once in a while an embryo will split from one into two. So how do intended parents decide how many embryos to transfer to their gestational carrier so they can maximize their chances of achieving a pregnancy while also minimizing the odds of high-order multiples? (defined as triplets or more, though some intended parents or even gestational carriers wish to minimize their chance of carrying twins)
Obviously the first step is listening to your embryologist and your reproductive endocrinologist. They’re the ones most familiar with your unique medical history and the quality of the embryos you’ve created. By considering all of the relevant medical factors, they can give you their professional opinion on what they feel is best in your particular case, based on the information they have at the time of the transfer.
However, you and your gestational carrier should also be on the same page with what you’d like in an ideal scenario, and that discussion should take place as you’re matching with one another and before you sign contracts. If you feel strongly about transferring two embryos and your surrogate only wants to transfer one, you could end up in an uncomfortable position at your transfer, one that could have been avoided had you discussed it with one another earlier.
Again the key here is “ideal scenario.” You should come to an agreement on what your ideal scenario is (for example, transferring two 5-day old blastocysts) as well as discuss other possibilities. While you can’t possibly make firm plans that cover every different potential embryo scenario you might encounter, you can talk through how you feel about variations that differ from your ideal. That way, when your transfer day arrives and you have the latest information about the quality of your embryos to consider, your decision making process will be much easier and less overwhelming.
In the rare but possible case that an embryo splits and your surrogate is pregnant with more babies than one or both of you are comfortable carrying, what happens next? What’s in the best interest of you the intended parents, your gestational carrier, and your unborn babies? Although no one likes a high-risk pregnancy, few people are comfortable with selective reduction, either.
While transferring only the amount of embryos that you would be like to be carried to term is the best way to avoid a difficult situation, that strategy does not always prevent it from happening (an embryo splits after transfer about 1% of the time – so the odds are slim, but not non-existent). You and your gestational carrier should discuss the issue of selective reduction in the case of not only grave birth defects, but also in the event that you end up with more babies growing than you intended.
The day of your embryo transfer is a very exciting one, for you as intended parents as well as for your gestational carrier. With good medical care and advice along with honest and open communication the months prior to your transfer, you can maximize your chances for a successful pregnancy while also minimizing the odds of complications. Just as in life, there are no guarantees in IVF, but careful planning and forethought along with an open-minded dialog between all parties can definitely put everyone in a position for success.