Egg Freezing and IVF: How Many Eggs Do You Need?

Again, this entry has many elements that apply to standard fresh IVF cycles.

Here we’re trying to close in on the real question, “If you do egg freezing, will it help you have a baby?”

Well, it will really does help if you can make some eggs. Sorry if that sounds too obvious, but the more you make the better your odds of this whole thing working years down the line. Just as with any IV F cycle, egg production is based on the number of eggs that are still in your ovaries, and how they respond to the medications.

Much of this is loosely related to a woman’s age but there are a number of other factors involved. The dose of drug can have an effect on the number of eggs produced; the more drug the more eggs, but only to a point. In other words, if your ovaries are full of eggs, a dose of 450 units per day may be way too high and lead to danger, but a dose of 225 might get you 15-20 without much of a risk. However, if your egg reserve is marginal, 225 may make 6 eggs, 450 may make 8, but going over 450-600 probably will not get you any more.

There are papers and book chapters written about how to stimulate ovaries to get the maximum response in women with limited ovarian reserve. For today let’s just say that one of the hardest things we do is try to get the ovaries to produce more eggs than they want to. There are numerous stimulation protocols that we try, and sometimes we get more eggs than expected, but sometimes we get fewer. In very many cases, it may be that it wasn’t the doctor’s choice of medications; it was just the woman’s body being more or less cooperative during that cycle.

Testing for ovarian reserve is one way to get a general guess about your response, but it’s not always helpful. A bad ovarian reserve test is not good news; a favorable result does not guarantee results. There are many of you reading this who despise ovarian reserve testing and some of you who have proved doctors wrong, having babies after being rejected for bad day 3 blood tests. I understand this. I think the testing is should at least be performed to give you a general idea about your prognosis so that the expectations can be based on all available information. Included in this is an ultrasound examining the antral follicle count. Again, not a perfect test, but it will help you get closer to answering the question, “Will this help me?”

You will not know about your egg production until after you start your cycle. Let’s say you have had your consultation and testing and things look reasonably positive, so you decide to give it a go. Fine, but you need to know a few more things. Especially if you have never been on the fertility injections before, the number of follicles that you develop will be a mystery until you are on the drugs for 5-8 days. By then your follicles will have begun to grow and your doctor can count them up and let you know how you are doing. Unfortunately, some women will be producing a low number of eggs.

Follicle number does not equal egg number. We see follicles on ultrasound; we get eggs from the follicles. We never really know how many eggs you will get until we try to take them out on the day of retrieval, but we have certain expectations. If we see 10 good sized follicles, we expect to get 8-10 eggs. There are endless examples of variations. For instance, let’s say you are ½ way through the stimulation and it looks like there are 5 follicles. But there may be others that look very small, maybe too small, but over next few days the small ones may catch up, giving you say 9-10 decent follicles on the day of retrieval. Another possibility is that you have 5 good ones and 4 tiny ones at retrieval, and even the tiny ones that never caught up in size, still give up good eggs (this is not typical).

The opposite could also happen. Your doctor may see 10 follicles and only retrieve 5 eggs. How is this possible? It’s not uncommon to have fewer eggs than follicles. Some doctors feel that there are some follicles that do not have eggs in them. I think this is possible but not very common. It may also be that the egg is in the follicle but it just does not come out through the needle. This I think is more common. Generally the egg is very loosely attached to the inside of the follicle, but if it’s stuck to the inside, it may evade the needle.

So how many eggs do you need to have a successful egg freeze (or fresh ivf cycle for that matter)? Again the too obvious answer is the more the better. However 10-15 is a good yield. More than that is a bonus. It is true 30 may be better than 15, but most women do not make 30 so that should not be your goal. Estimates in the 10-15 range usually do not prompt much patient/doctor discussion, however when the estimate is lower, the talks become more frequent and important.

Usually your doctor is close enough with the pre-retrieval estimate, so assume it will be close. If a low number is estimated you will need to make a decision, with the help of your doctor, about having the retrieval or not. Yellow flags should rise if you are told there are less than 10 follicles, and red flags should rise if you are told there are 5 or less.

Overall there is just no absolute egg number cut-off for cancellation. Some programs may have strict guidelines, but most do not. We all understand the dilemma. If there are few, your odds of success are lower, however if there are few, it means your fertility may be passing. Getting, say, 4 eggs now may be better than nothing, because as months pass, you may make fewer in the future. Stopping without the retrieval, and restarting in a short amount of time, using a different protocol, would probably be the best choice. However, even with making changes you may have the same or even fewer next time. Now I picked 4 follicles as just one example, but the discussion needs to be tailored for 3,5,6,7 etc. Your age, previous response and your desires all need to be taken into account each time.

Your doctor needs to take the information above and formulate your chances of not just getting eggs, but of getting a baby from your egg freeze cycle. This applies to all cases, good egg production or not.

You will get the most accurate information if you are using an egg freezing practice that has results, not just freezing experience. Experience and results with the thaw and transfer is very important; you need a program with a track record. You need to know their experience in going from eggs to babies. Many busy egg freezing programs have no results because they have not thawed any of their eggs yet. Others have done less than a handful of cases.

I do want to refer you to the NYU Fertility Center web site section on egg freezing.
http://www.nyufertilitycenter.org/egg_freezing.
Spend some time going through all of the pages, the information is very helpful.

Thanks to the fantastic research and efforts of the doctors listed there, NYU is known for its egg freezing practices and results. I could summarize the site here, but in the interest of accuracy, go directly there to get it from the horse’s mouth. The results are frequently updated.
The breakthrough, as mentioned on the site, is that we believe that our egg freezing success rates will remain similar to our fresh IVF success rates. Therefore, it will help if you have your eggs frozen at a program with excellent fresh IVF pregnancy rates. If their fresh IVF rates are low, their egg freezing rates will probably be low too.

Not all egg freezing programs can show good data to support good results (2 out of 4 pregnant is not enough.) There are a few who can, so if you are interested in egg freezing, you need to seek out the good ones. Details are sparse, so I really only know about NYU. Odds are there is not a quality program near where you live, so if you can swing it, it may be worth traveling.

Even the NYU rates need to be clarified. Most of the studies at NYU and elsewhere on egg freezing have been performed with good prognosis, younger women. We are not positive that older women’s eggs will freeze and thaw well. They probably will, but there is no data yet to prove the case. We don’t know how long eggs will last in the freezer. We do know there have been children born from sperm and embryos frozen for over a decade, so eggs should be able to last at least as long, but again there is no proof yet. Egg freezing is very new and still considered experimental you do need to freeze your eggs at the right place.

We and other doctors can not completely predict the landscape 5-10 years down the road. We are optimistic that our pregnancy rate estimates are correct. However there is a chance that due to unforeseen circumstances, the rates will be lower. You just need to know this going in. It may also be possible that the outcomes will be better than we had hoped.

Next time we will cover what you should know about what happens after the eggs are retrieved and how the cost structure works.

Thanks for reading and don’t forget to read the disclaimer entry 5/17/06.

Dr. Licciardi