Sunday, April 30, 2006

How many embryos should I transfer ?

Deciding how many embryos to transfer remains the most difficult decision patients and doctors need to make in an IVF cycle. In a perfect world, if IVF technology ensured a 100% pregnancy rate, everyone would transfer only one embryo, so that all patients would have one baby ( actually, many would transfer two so that they could have twins) - and then there would be no need for websites like this one !
Achieving this goal remains the holy grail for IVF doctors , but the technology is still not perfect, and because we cannot regulate the implantation process, we still cannot ensure that each embryo we transfer will become a baby. One easy way of improving the chances of achieving a pregnancy in an IVF cycle is by transferring more embryos. However, as with everything else in life, the price we pay for this is that the risk of having a multiple pregnancy also increases. Obviously, there is a point of diminishing returns, and by transferring more than 4 embryos at a time, one only increases the chances of a high order multiple birth, without increasing the chances of getting pregnant.
Ideally, patients should be free to choose for themselves how many embryos to transfer - after all, they are the ones who have the most at stake. However, because the burden of caring for high order multiple pregnancies ( and the triplets and quadruplets who are born as a result of these) falls on the government, many countries have strictly regulated the numbers of embryos which can be transferred back, and in UK and Australia, doctors are allowed to transfer only 2 embryos. While this is quite sensible and appropriate for the majority of infertile couples ( young women doing their first IVF cycle), this is not sensible for older women, or women who have failed multiple IVF cycles in the past. However, the rules in these countries ( as it typical of most bureaucracies) does not allow for any individualisation or flexibility, which means that poor-prognosis patients are poorly served by these rigid rules.
In such difficult patients , our pregnancy rates are very high, because we can transfer more embryos in them ( unlike clinics in UK and Australia, where the number of embryos which can be transferred is limited by law). While transferring more embryos does increase the risk of high-order multiple pregnancies, this risk is negligible in difficult patients ( for example, the older women or women with previous failed IVF cycles). In our clinic, we customise the number of embryos we transfer for each patient we treat, rather than just blindly follow a guideline ( which has been laid down for the general population, without considering each individual's specific problem).
Are we being irresponsible by transferring too many embryos ? I don't think so . I understand it is a calculated risk, but I feel our approach is more enlightened, because we are allowing our patients to make this decision for themselves. After all, it is the patients who need to suffer the consequences of this decision, so why not let them decide for themselves ?
As I explain to patients, there are 3 possible outcomes in an IVF cycle: one good, and two bad.
The good outcome is when they get pregnant with one baby ( or two, for most infertile couples). This is a happy ending, and most couples will forget the trauma of decision making once they get to this point.
There are two possible bad outcomes:
a. not getting pregnant at all
b. getting pregnant with a high order multiple ( triplets or more).
From a government's point of view, they would prefer that patients not get pregnant at all ( outcome a) rather than have a multiple ( outcome b). This is because if the patient fails to conceive, this is her personal private loss. However, if she has a multiple, then the government needs to pay for the medical care of her newborn babies - and this can be very expensive !
However, from the patient's point of view ( especially if this is the third or fourth attempt), then not getting pregnant is a major disaster. If she gets pregnant with high order multiples, this is still the lesser of two evils, from her perspective. She can choose to carry the pregnancy ( taking the risks of prematurity into account, after being counselled about these); or she can opt for a selective fetal reduction. While it is true that this can be a heart-wrenching decision to make, the fact remains that it is being done to save the lives of some of her babies , and this therefore acts like a safety net ( much like abortion does when contraception fails). I advise my patients to "take the path of least regret", so that they have peace of mind they did their best !

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