It might be scary when we first go over the numbers together, but this is exactly how conception works in the natural process as well. With IVF, we have the privilege of seeing this natural attrition happen in real time in a laboratory. As you may know by this point in your research, the first phase of IVF is to stimulate the ovaries and create as many dominant follicles as possible.
One becomes dominant and the rest are reabsorbed back into the body. That dominant follicle releases an egg into the fallopian tube during ovulation and is fertilized by sperm at that point. With IVF, we manipulate that normal cycle by getting as many of your follicles to grow into that dominant phase as possible instead of just the one.
It takes a special mix of medications to make this happen, and when the growth phase is complete but before ovulation , we remove each egg from its follicle through a process called an egg retrieval. Unfortunately, not all 12 eggs will be viable, or useable. Because only mature eggs will fertilize. While our goal is to have all mature eggs, they naturally grow at different paces and thus will leave us with some variation in viability. That leaves us with 10 viable eggs.
The fertilization process has to happen naturally overnight with partner or donor sperm in a laboratory. This happens one of two ways: conventional insemination or ICSI. Both are very effective and used for different reasons. Conventional insemination is when the egg is surrounded by a deposit of sperm in a petri-dish. Because one sperm will find its own way into the egg for fertilization, this mimics natural selection as best we can in a laboratory setting. There are multiple reasons to choose this method, one of which being good sperm quality.
ICSI , or intra-cytoplasmic sperm injection , is when an embryologist selects a single sperm and manually injects it into the egg, fertilizing it that way. There are several issues involved with this: More eggs will give us more fertilized eggs — which results in more likelihood of having good quality Women that respond well to the stimulation drugs sometimes also have better egg quality — and therefore could be more likely to have some high quality embryos.
Women and years old have low live birth rates with low egg numbers. Success rates are much better when relatively high egg numbers are obtained. All age groups have very low success rates with less than 3 eggs retrieved This is another example of decreasing egg quality with increasing female age. Contact Us. Share on facebook. The study indicated that to produce 1 and 2 euploid embryos, 5 and 14 oocytes would be required at age However 10 and 24 oocytes would be required at age Hence, the older a woman is the more eggs have to be retrieved in order to increase the chance of obtaining an additional chromosomally normal euploid embryo.
The cumulative pregnancy rate refers to the chance of a pregnancy after a single stimulated IVF cycle including both fresh and frozen embryo transfers resulting from that cycle. This research helps to explain why cumulative pregnancy rates after IVF seem to improve in cycles with a higher egg yield. The more chromosomally normal embryos there are, the more transfers are possible, with an inevitably better cumulative chance of pregnancy and live birth. Chromosomally abnormal aneuploid embryos are unlikely to develop as pregnancies, and, if they do, sadly frequently result in miscarriage.
A number of studies 1, 2 published recently suggest that cumulative live IVF birth rates increase significantly with the number of eggs retrieved. This association is not evident in the initial fresh cycle of treatment, where birth rates might be even inferior when a high number of oocytes is obtained 1, 3. This is most likely due to an adverse effect of intense ovarian stimulation on the receptivity of the endometrium as has been convincingly demonstrated 4, 5.
This study also provides evidence that aiming for a higher egg yield during ovarian stimulation does not seem to compromise the quality of the eggs obtained. This has been debated for years but recently accumulated evidence suggests that a detrimental effect of intense ovarian stimulation on egg quality is unlikely. On the contrary, obtaining a higher number of eggs will probably lead to a higher number of competent eggs and, as the present study has shown, to more chromosomally normal euploid embryos.
While this study does provide strong evidence in the ongoing debate over the importance of egg numbers as determinants of IVF success, any attempt to propose an optimum number of egg collected needs to take into account many other parameters such as:.
It should not be overlooked that aiming for a high number of eggs usually more than 15 can increase the risk of ovarian hyperstimulation syndrome OHSS , a potentially serious complication of ovarian stimulation.
However, newer IVF protocols can substantially reduce this risk, allowing fertility specialists to maximize the results from a single IVF cycle and thereby reduce the financial, physical and emotional cost of fertility treatment. Increasing the oocyte yield should always be performed safely which means an individualised approach should be discussed with your fertility specialist. Patients wishing to know more about this study, including how to increase their chance of pregnancy from IVF treatment, should speak with their local fertility specialist:.
The optimum number of oocytes in IVF treatment: an analysis of cycles in China.
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