| IVF Pregnancy rates |
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Understanding IVF Pregnancy RatesThe purpose of this section is to help patients understand:
IVF Pregnancy rate definitionsNumber of cycles: This is the number of IVF treatments that were STARTED in a particular age group. IVF cycles can be cancelled or stopped at various times after starting. For instance, an IVF cycle can be cancelled :
A program with a very low IVF cancellation rate: This might be bad because... It could mean that an IVF program has very selective criteria for who they will allow to start an IVF cycle (Strict patient selection will artificially inflate the pregnancy rates). This might be good because... It could mean that they are very liberal in allowing patient to finish a cycle once started. For example, let’s say a woman is having a very poor response to fertility medications and she has only one egg developing. Some programs might cancel that cycle before the retrieval is performed because the likelihood for pregnancy is so low. If a program does not cancel that cycle, their pregnancy rates will be lower because of their generous policy. A program with a very high IVFcancellation rate This might be bad because... A program may be trying to inflate their pregnancy rates by reducing the number of poor prognosis patients who make it to egg retrieval or embryo transfer This might be good because... They could be doing testing on embryos using PGD and cancel many cycles that would otherwise have resulted in babies born with birth defects. Pregnancy You would think this would be straightforward. The CDC considers a cycle to have resulted in pregnancy only if the pregnancy progresses far enough to be seen on ultrasound. In other words, if a pregnancy is established and verified by blood tests but a miscarriage occurs before it is seen on ultrasound, the CDC will list that as not being pregnant at all. Thus, if an IVF clinic sees many patients with a high risk for miscarriage, their pregnancy will be artificially lowered. IVF clinics with a recurrent pregnancy loss program may be at a significant disadvantage when comparing their pregnancy rates to clinics without such a program. Live birth The CDC considers babies live born if they have spontaneous heartbeat and breathing. This is pretty straight forward. However, it can be deceiving. For example, lets say a poor IVF program decides to transfer seven embryos into the uterus and a quintuplet pregnancy results. The babies are born prematurely. Two are born alive but die in a few hours. This is counted as a live birth. On the other hand, consider an IVF program that transfers one embryo and a single baby results. The baby is lost in the uterus just prior to delivery because the umbilical cord became entangled around the babies neck. Because the baby was not born alive, it would be recorded in the statistics as "not pregnant". As you can see, relying on pregnancy rates to determine the worth of an IVF program is difficult and misleading. Average number of embryos transferred This is another important number. This may be the best measure of an IVF program. The less embryos an IVF program needs to transfer, the better. For example, consider two programs that have exactly the same patient population, have the same criteria for allowing patients to be treated with IVF, the same criteria for cancellation, and the same pregnancy rate. One program however routinely transfers four embryos and one program transfers two embryos. The IVF program that transfers the fewer embryos is more efficient and is said to have a higher implantation rate. Multiple pregnancy rate This is a measure of safety. Multiple pregnancies carry higher risks for the mother and the babies. All IVF programs should strive to keep their multiple pregnancy rate as low as possible. Often, IVF programs that have inconsistent results will transfer large numbers of embryos to help maintain the appearance of a higher pregnancy rate. Of course, by doing this, they will occasionally get high order multiple pregnancies and put their patients at greater risk. |
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| Last Updated ( Friday, 26 October 2007 ) |
