Maybe you’re aware, maybe you’re not aware. Either way, I’ll let out a little secret: American infertility doctors are much better than European infertility doctors. There. I said it. Now let’s start a chant: USA! USA! USA!
Wait… Didn’t we explicitly look for treatment in Europe? That seems like a pretty dumb thing to do, with this newfound knowledge of ours. Let’s investigate a little further: are American infertility specialists simply better? Do they have higher success rates?
My momma always told me to listen to what the science says. Ok, fine, she never said that. But I’m saying it now! I did what every cool little boy always wanted to do when he grows up: read the scientific literature.
What the Science Says
Only a few studies have investigated continental differences in IVF outcomes. Two of which were clinical trials conducted on both sides of the pond and two other studies compared data from government agencies.
1. In 2010, Baker et al.1 published a study of around 300 patients. The European patients had a 27.6% live birth rate while American patients had a whopping 38.2% birth rate.
Score: USA 1 – Europe 0.
2. Then, in a 2012 clinical trial with about 1,500 patients divided over the 2 continents (Boostanfar et al.2) it is reported that the live birth rate and cumulative pregnancy rate (pregnancy after fresh and frozen transfers as part of a single cycle) were indeed substantially higher in the US than in Europe (between 5 and 15 percentage points higher).
Score: USA 2 – Europe 0.
Hmmm. What gives? Is there actually some merit to this claim?
The CDC and ESHRE
Let’s try to look at some cold hard numbers of ALL American patients and (almost) ALL European patients. For this epic battle to happen, we look to the Center for Disease Control and Prevention (CDC) in one corner, and the European Society of Human Reproduction and Embryology (ESHRE) in the other.
In the USA, fertility clinics submit data to the CDC. The CDC, in turn, shares all this information on their website in an annual report. You can look up any US clinic in this pdf file. The most recent report (as of writing this in December 2017) summarizes success rates from 2015.
In Europe, success rates are not collected by a national organization, since, well, there is no “European” nation and I guess it’s not one of EU’s priorities to keep track of this. Luckily, there is a consortium of researchers who aggregate data from most European countries and report on this data annually. The ESHRE. Their most recent report was published in 2017 and summarizes European IVF success rates for 2013.
Let’s see how these two continents stack up when it comes to infertility treatment outcomes:
After weeks of combing through these looonnnggg reports (you believe me, right?), it seems that we’re rather limited in what we can actually compare if we want to compare apples to apples. The whole methodology of data collection is simply different. Two pretty simple metrics can be compared though are:
- The per cycle pregnancy and delivery rates of all patients who underwent a fresh IVF cycle with own eggs (with or without ICSI)
- The per cycle own egg pregnancy and delivery rates of patients less than 35 years of age
Rates represent the most recent data available for Europe and USA as of 2017. USA rates taken from CDC 2015 Assisted Reproductive Technology: Fertility Clinic Success Rates Report (page 21). European rates were taken from the 2017 ESHRE report (Calhaz-Jorge et al. Supplementary Table SIX and SX). European values were originally reported separately for IVF and ICSI. Values reported in this table are weighted by the prevalence of ICSI(70%)/IVF(30%). CDC rates are only published split by age groups. The overall CDC success rates were therefore calculated by weighting the rates of each age-group by the number of cycles in the respective age group.
- For each fresh IVF cycle, American patients have a 3.2 percent points better shot at delivering a baby. The difference is less when it comes to pregnancy rates: there is only a 1 percent point higher chance of pregnancy for American patients.
- Looking at the <35 years of age group, differences are a bit more apparent. There is a 5.7 percent point difference in delivery rates, in favor of the USA.
Score: USA 3 – Europe 0.
Reasons the USA reports better IVF success rates than Europe
In both Europe and the USA, ICSI is utilized equally often (70%3), so it’s unlikely that fertilization method is the reason for American supremacy.
Just as we did above, Gleicher et al. (20064 and 2007
5) compared (old) CDC and ESHRE data. In those papers, the authors reported some analyses of IVF outcomes from some time ago (2001 and 2002). And while continental differences are again apparent, this doctor has some insights into what could cause such a stark discrepancy in apparent success rates:
- European doctors are more hesitant to cancel cycles than American doctors, which could mean that pregnancy and delivery rates are lower in Europe since “low-quality” cycles are more likely to be canceled altogether in the US.
- Some European countries have laws restricting who can donate eggs: for example, only patients referred for infertility problems themselves can donate (resulting in those donated eggs likely being of lesser quality).
- Europeans often have insurance coverage of IVF, whereas American patients do not. As a result, twice the percentage of Europeans undergo IVF compared to Americans. Even though no background data is available, we can speculate that American patients are more likely to be of higher “social standing”, higher educated, healthier, and different in other socioeconomic factors, considering they need to have the financial means to even consider infertility treatment.
- And let’s not forget the most obvious difference between the continents: American doctors (throughout the years, and still to this very day) are much more likely to transfer 2 or more embryos, whereas most European doctors prefer to stick to 1 embryo transferred.
OK. Looking at the big picture, the differences between Europe and the US maybe aren’t THAT great after all. And the differences we do see have some pretty plausible explanations (although it’s hard to prove any of this with actual numbers!).
Again. What does the science say?
Remember the studies I cited in the beginning of this post? They did, in fact, show much better outcomes in America than in Europe. I want to leave you with some final quotes from the very doctors who wrote these articles. Just to highlight that you should always be a bit apprehensive and skeptical when interpreting studies.
Boostanfar et al.2 say (emphasis mine):
- “Our data indicate that the patients recruited in North America had a slightly higher ovarian reserve and had fewer previous IVF attempts”
In other words, even though patient groups between North America and Europe were similar in many ways in this study, American patients had both more retrievable eggs and had less history of infertility. In other words, we can assume from the get-go that the European sample was less fertile.
Boostanfar et al.2 also conclude that:
- “… the rate of multiple pregnancies was twice as high in North America than in Europe, owing to more frequent double embryo transfer than single embryo transfers in North America, whereas elective single embryo transfer would be indicated for the majority of this relatively young IVF population”
Translation: in younger patients (which was the case in this study!), single embryo transfer is recommended. But, and this might be a cultural difference, North American doctors tend to transfer more embryos each cycle than European doctors do. Multiple embryo transfers result in higher success rates but also results in a higher number of twins, triplets, or even octuplets…
Baker et al.1 offer similar reasons explaining continental differences, but also notes that in their particular study:
- “The percentage of embryo transfers performed at the blastocyst stage (Day 5) was 26% in the US compared with 2.2% in Europe, likely a reflection of preference or better cohort of embryos available in the US.”
To rephrase: in this particular study (with “Europe” only being represented by France and Hungary) practically no embryos were transferred at the blastocyst stage in Europe, while a quarter of embryos transferred in the US reached this more advanced stage. Basically, embryos were transferred at a later stage in the American sub-sample, a known factor leading to higher success rates (see page 37 in this CDC report).
Yes. It’s true that the American statistics look better. There’s no denying that. We see it in the CDC vs. ESHRE data, and we see it in the scientific studies. Having said that, to me at least, the differences seem much, much, less drastic than we were initially led to believe. Especially when looking at cold hard nation-wide numbers. Numbers even fluctuate a lot from one year to the next. In fact, so many factors influence success rates, that the differences we do see seem kind of… minor in comparison.
Final Score: USA 3 – Europe 2.5 (?)
I want to end by saying that YOU should make up your own mind. Personally, I’m not worried that (most) European fertility clinics are bad. Especially if you are even remotely careful with which clinic you choose (and that goes for both continents!).
Footnotes & References
1. Baker VL, Jones CE, Cometti B, Hoehler F, Salle B, Urbancsek J, et al. Factors affecting success rates in two concurrent clinical IVF trials: an examination of potential explanations for the difference in pregnancy rates between the United States and Europe. Fertil Steril 2010;94:1287–91.3 papers.
2. Boostanfar et al. 2012. A comparison of live birth rates and cumulative ongoing pregnancy rates between Europe and North America after ovarian stimulation with corifollitropin alfa or recombinant follicle-stimulating hormone. Fertility and Sterility, 97(6), 1351-1358.
3. 69% USA (CDC, 2013) and 70% in Europe (ESHRE, 2013).
4. Gleicher N, Weghofer A, Barad D. A formal comparison of the practice of assisted reproductive technologies between Europe and the USA. Hum Reprod 2006;21:1945.
5. Gleicher N, Weghofer A, Barad D. Update on the comparison of assisted reproduction outcomes between Europe and the USA: the 2002 data. Fertil Steril 2007;87:1301.