A SIMPLE QUESTION WITH A NOT SO SIMPLE ANSWER
The first thing I wanted to know when I started thinking about IVF was – how successful is it? You know, “what are my chances of getting pregnant?”, and “how many cycles will I need to go through to have a baby?” These seem like pretty simple, sensible questions, but as anyone who has dared dip a toe of interest into the vast deep sea of fertility treatment has found, these are heavily loaded questions and the answer is far from simple.
As I soon discovered, just about every fertility clinic, statistical data authority, or online calculator reporting IVF success rates draw their information from one of the following legislated sources where the answers are not always as they seem (to an amateur anyway):
- In the US IVF reports are published by the Centre for Disease Control and Prevention (CDC) in collaboration with the American Society for Reproductive Medicine (ASRM) and the Society for Assisted Reproductive Technology (SART).
- In Europe, the European Society for Human Reproduction (ESHRE) collects and reports IVF statistics from 39 countries through their European IVF Monitoring Program.
- IVF results from clinics in Australia and New Zealand are reported annually by the National Perinatal Epidemiology and Statistics Unit (NPESU) a research unit at the University of New South Wales in Sydney.
Falling For The Amateurs Trap!
After my first quick dive through the vast information available from these sources in a bid to understanding MY chances of success, I came away thinking I had the information I needed and skipped merrily along thinking things looked pretty promising. A few weeks later, on closer inspection however, I found that what I thought to be the answer to my statistically informed chances of success with IVF, was in fact a serious misunderstanding of what seemed (at first glance) to be straight forward numbers.
The consequences of my error meant that I underestimated how much time, money, and emotional investment having a baby was going to take. And even worse still, I didn’t know my chances of failing were as high as they were!
I am so thankful that women, like me, who are struggling with infertility, have the option of IVF and I am at the moment going through an IVF cycle – so I am not saying it is not worthwhile. I only think it is important that we are as informed as possible about our chances.
I get on my soapbox…
While I’m not on the list to receive a Nobel Prize for mathematics any time soon, I do have enough understanding of how probabilities work to know that roulette isn’t a very viable long term career choice. Figuring that if I could make this costly error in analysis, there must be at least a few others out there that have, or will, make the same mistake as me….If I could share one thing with others about #eggfreezing or #IVF, it would be how misleading success rates can beClick To Tweet
If there was one thing I could share with a friend or family member considering egg-freezing or IVF, understanding how success rate statistics can mislead you would be one of the most important things.
Knowing that understanding the problem is only the beginning of a solution, I have also included a summary below of the best information out-there giving us “The Statistics We Really Need”.
One of the first mistakes I made when looking at the success rate of IVF, was assuming that pregnancy rates meant ‘having a baby’. While in retrospect this might seem like an obvious error, I still made it, and thought I better check that we’re on the same page before going any further. Success rates of IVF are normally measured in terms of pregnancies and/or delivery rates with the results for any group of women never being the same due to the unfortunate reality of miscarriages and still-births. When people talk about reported “pregnancies” rates, they are usually referring to “clinical pregnancies”, which are defined as a pregnancy that is known to be ongoing at 20 weeks.
“Live Birth” or “Delivery” refers to the birth of a baby, or babies in the case of multiple births, with the birth of twins or triplets etc. counted as one live birth or delivery. To me live birth rates are the most important metric when looking at IVF success rates since the whole purpose of the IVF is to have a baby, rather than to just get pregnant right?
While I don’t mind a bit of math, my husband proudly admits he “loves it” and so I had him prepare the following detailed analysis. Whilst I’m pleased that we can provide you with such a comprehensive explanation of how the IVF success rate is calculated and why it can be misleading, if you want to just cut to the chase please feel free to skip ahead to “What These Results Mean For You”. Or if all you want is to figure out what your own personal likelihood is of having a baby through IVF, we have put together for you what I am pretty sure I can claim to be, at this point in time, THE MOST reliable calculator you are going to find anywhere online (I’ve looked!).
This IVF Success Rates Calculator will help you to quickly and easily calculate what the actual IVF outcomes are for real women relevant to your similar situation (IVF success rates by age, specific fertility problems, your chosen IVF treatment method, etc) using the most recently published population statistics for IVF. My husband spent literally about a month putting it together using mathematical equations like binomial probability distribution (whatever that even means..?) to calculate out my own possible success rates. My hope is that by doing the calculation it may help you, like me, feel more knowledgeable and prepared for the journey. For all those interested in the detailed statistics, you may venture at your own risk into the land of mathematics below.
The success rate of IVF is almost always recorded and reported on a per cycle or per embryo transfer basis. Some typical examples are shown below: Figure 1. Success rates of IVF for each embryo transfer reported by a commercial group of fertility clinics for patients using their own eggs. Figure 2. Success rates reported by the CDC in 2012 for patients using their own eggs.
Percentages on a per cycle basis, are calculated by taking the number of pregnancies, and live births etc. then dividing them by the number of egg retrievals initiated.Per Transfer results are calculated by taking the number of pregnancies, and live births etc. then dividing them by the number of times fertilised embryos placed back into the woman’s uterus.The differences in the per cycle, and per transfer figures are due to cancellations (cycles were egg retrievals did not go ahead as planned), and cycles where no eggs were successfully retrieved, fertilised, and transferred.
I’m NOT suggesting that anyone out there is intentionally trying to mislead people as most sources are very clear about the basis of the information they are providing. The website presenting Figure 1 for example states, “We measure our success in our ability to help patients conceive as quickly and simply as possible.” They are presenting this information to support their commitment to provide a world-class service. The problem comes when we take the probabilities presented to mean something they don’t. What most women really want to know is what the chances of success are for the average women when she commences her IVF treatment – and the examples above do not tell us this. The actual success rate we want is calculated by taking the number of live births, and dividing them by the total number of women who started. Because many women will under-go multiple cycles in any given year, the results on a per woman basis can be significantly different to the per cycle, or Example 1: Comparison of per cycle, per transfer, and per woman success rate of IVF for women aged 35-39 undergoing fresh IVF cycles using their own eggs.
- Number of women undertaking IVF = 10,432
- Initiated cycles = 5,046
- Embryo transfer cycles = 11,331
- Clinical pregnancies = 3,479
- Live deliveries = 2,564
To explain these results in plain language: while 23% of cycles initiated, and 31% of IVF cycles undertaken resulted in a pregnancy, only 25% of women who under took IVF in 2012 actually ended up with a baby. The other three quarters of women aged between 35 and 39 who underwent one or more cycles during the year ended up with nothing. What we cannot conclude from these results is that if a women aged between 35 and 39 undergoes 5 cycles, her chances of having a baby will be 85% (i.e. 17% x 5). This is because as the “per woman” results show, a large percentage of women who undergo IVF, unfortunately, do not actually succeed at having a baby ever.
Even the experts agree that the current reporting methods are not adequate!
The current reporting of IVF outcomes is confusing at best, and inadequate for public consumption at the very least (the purpose to which they were created). Even many industry leading experts seems to believe an overhaul of current reporting on a per cycle basis that is needed. A critical opinion piece published in the American Journal of Obstetrics and Gynecology in 2015 identified eight references from various recognised fertility experts who have advocated “substituting the current cycle centered reporting system with one focused on a patient-centered paradigm… [this being a] system, …capable of more faithfully representing the total reproductive potential of any one initiated cycle…” Unfortunately however, it seems the “consumer-centred imperative” of public reporting of IVF outcomes by the CDC and SART seem unlikely to improve in the near term and so we’ll have to make do with what we DO have. Again, if you are interested in further exploring the probabilities of IVF success rates by age, success on a per cycle, per transfer, and per woman basis for various fertility health diagnosis, and IVF treatment options please try our IVF Success Rates Calculator. This useful tool helps you to quickly and easily see the ACTUAL IVF outcomes for women similar to you using population statistics. Play around with input options to see how various changes in IVF treatment methods can affect the probable outcomes.To know what your true odds are when undergoing multiple cycles of #IVF, you'll need to look at cumulative rates.Click To Tweet If you are considering egg-freezing or undergoing IVF and you want to understand your chances of having a child, the “success rates” you really need are what is referred to in the industry as the “cumulative success rates”. The cumulative success rates describe the probability of a woman having a live birth (delivery) after undergoing multiple IVF cycles over a number of years. It is not cycle based, time-based, or related to the number of transfers a woman undergoes during her treatment. To look at it another way, the flip-side of cumulative success rate is the chances that IVF will fail you.
Cumulative Live Delivery Rate Definition:
- Cumulative Live Delivery Rate = the probability that a woman will have a baby over the course of her IVF treatment (not just during one cycle, transfer, or year)
- 100% minus the Cumulative Live Delivery Rate = the probability that a woman will not give birth to a baby after multiple IVF attempts.
Professor Barbara Luke (Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University), and Dr Morton Brown (Department of Biostatistics, University of Michigan), and other leading researchers published cumulative success rates observed for all women in the SART database who underwent IVF using their own eggs during the years 2004 – 2008 inclusive (Luke B, Brown MB et. al 2012. The data they used for their statistical analysis was from 246,740 women, with 471,208 cycles from clinics across the United States representing a massive representative dataset. The results from this study are summarised in the table below.
Table 1. Cumulative Pregnancy Rates and Live Birth Rates for Women in the United States who started their first IVF treatment cycle between 2004 and 20084. <
Using the statistical data collected across all IVF clinics in Australia and New Zealand, Macaldowie and Wang et. al 2013 present the cumulative success rates of women who started their first IVF treatment using their own eggs during 2009–2011. Women in this group were followed from the start of their first fresh IVF cycle through subsequent fresh and thawed (frozen embryo) cycles until the end of 2011, or delivery of a baby (if conceived in 2011). The results from this study are summarised in the table below.
Table 2. Cumulative Pregnancy Rates and Live Birth Rates for Women in Australia and New Zealand who started their first IVF treatment cycle between 2009 and 2011.
Note, these results do not include the successful pregnancies and births for women in this group who made additional IVF attempts in 2012, and 2013 and hence may be an under-estimate of the actual cumulative success rates for this group of women. In 2014, the same authors published the cumulative success results for a sub-group of the women shown in Table 2, giving only the results for women who started in 2009. Because it is likely that most of the women in the 2009 group will have completed all IVF treatments by 2014, these results could arguably be the better estimate of cumulative success rates despite being a smaller sample size.
Table 3. Cumulative Pregnancy Rates for Women in Australia and New Zealand who started their first IVF treatment cycle during 2009.
Approx 6/10 women under 35 who do IVF will eventually have a baby but the odds are less than 20% after 40Click To Tweet These valuable results show that approximately 6 in 10 women under 35 years of age who start IVF will have a baby (and that 4 in 10 will not) over multiple courses of treatment. These odds reduce significantly after age 35 and the IVF success rates over 40 are less than 20%.
I would disappoint all the scientists and statisticians out there if I didn’t make a few final clarifications for anyone planning on using the cumulative live birth rates presented above in their smart fertility choices. The success rates shown are for large populations of women getting IVF and hence provide the average outcome across this diverse group of people. Depending on your particular diagnosis, the methods, technology, and the professionals that you choose for your treatment, your personal success rates are likely to differ from those shown. Some people are going to do a lot better than average and worse than average. It is using population averages.
So hopefully now that you have read this, you will feel a new sense of confidence when reviewing websites or talking to fertility professionals regarding your chances of success with IVF:
- You now know that most IVF success rate information is based on per cycle and per transfer statistics and that these results DO NOT tell you the probability that an individual woman will get pregnant or have a baby.
- You know to look for live birth or delivery rates and not pregnancy rates.
- You now know that cumulative success rates for live births are the answer to your likely success or failure if you choose to undergo IVF, and
- You now know that based on the most recent data, approximately 40% of women younger than 35 fail in their attempts at one or multiple IVF cycles, and that the IVF success rates over 40 rate rises to 80%.
If you are interested in further exploring the probabilities of IVF success rates by age, success on a per cycle, per transfer, and per woman basis for various fertility health diagnosis, and IVF treatment options please try my IVF Success Rates Calculator.
This useful tool helps you to quickly and easily see the ACTUAL IVF outcomes for women similar to you using the population statistics referenced in this blog and elsewhere. Play around with input options to see how various changes in IVF treatment methods can affect the probable outcomes.
This information has been provided to empower you (I hope it doesn’t depress you). Keep in mind the truism of “lies lies and statistics” and best of luck with your smart fertility choices! If you have any questions concerning this topic or want to share your personal experience with trying to figure out your likelihood of success with IVF I would love to hear from you in the comments below or on one of my social media pages. Thanks for reading and as always the best of luck in your journey!
I will continue with researching this information and in my next post for this segment, I explain how to calculate the number of IVF treatment cycles you are likely to need (assuming you are in the lucky group of women who will achieve success with IVF) and (of course) it’s not quite as simple as you might have guessed.
Data sourced from Macaldowie A, Wang YA, Chughtai AA & Chambers GM 2014. Assisted reproductive technology in Australia and New Zealand 2012. Sydney: National Perinatal Epidemiology and Statistics Unit, the University of New South Wales.
Macaldowie A, Wang YA, Chambers GM & Sullivan EA 2013. Assisted reproductive technology in Australia and New Zealand 2011. Sydney: National Perinatal Epidemiology and Statistics Unit, the University of New South Wales. Stan Williams;
Kevin J. Doody; Glenn L. Schattman; Eli Y. Adashi, Public reporting of assisted reproductive technology outcomes: past, present, and future, American Journal of Obstetrics & Gynecology, 2015.
Luke B, Brown MB, Wantman E, Lederman A, Gibbons W, Schattman GL, Lobo RA, Leach RE, Stern JE, Cumulative Birth Rates with Linked Assisted Reproductive Technology Cycles, The New England Journal of Medicine, 2012.