Statistics
At the Duke Fertility Center, we are fortunate to have one of the most successful IVF programs in the United States. However, infertility statistics can be a confusing and even misleading if you don’t know how they are calculated. Therefore, we recommend that you take a little time to understand the basics of infertility statistics so that…
- you don’t get a misleading impression about your individual chances of success or
- inadvertently, misunderstand the different way that two programs report their outcomes.
We believe that this investment of time will help you evaluate what is best for you and your family.The primary issue that can lead to confusion is not recognizing that infertility therapies often involve several steps and each step is a valid endpoint for evaluating infertility therapies. Each step is a hurdle that a couple must clear to reach the next step. Approximately 45 percent of couples (average female age 35) who begin a cycle of IVF will clear all nine hurdles and go home with a baby.
What this means is that a fertility programs can report different success rates depending on which numerators and denominators that they choose to use to represent their success.
For example, let’s make up a hypothetical example for Fertility Clinic A in 2008.
- 100 couples come to a fertility clinic to begin an ART cycle
- 95 meet criteria to begin superovulation
- 90 stimulate well enough to reach the oocyte retrieval step
- 88 have their oocytes fertilize and receive an embryo transfer
- 53 have a positive pregnancy test and
- 45 take a baby home
This means that
- 45% of couples who started a cycle took a baby home
- 51% of couples who had an embryo transfer took a baby home
- 53% of couples who started a cycle had a positive pregnancy test &
- 60% of couples who had an embryo transfer had a positive pregnancy test
All of these statistics are accurate. However, couples may mistakenly assess their chances of success if they don’t know how the statistics are being calculated.
The first number (45%) is the most relevant to a couple who has not yet begun the process and the last number (60%) might be most relevant to an embryologist, who only cares about laboratory variables. Patients should also realize that the variability of statistics becomes greater as the sample size decreases. Therefore, evaluating the success of programs or populations where there are not as many observations may be less accurate.
Other factors that play an important role in success are a patient’s age, reproductive history, diagnosis, prior therapy (type and duration), and results of that prior therapy.
A 25-year-old woman who had her fallopian tubes removed for three recent ectopic pregnancies has a better chance of success than a 38-year-old woman who has completed five cycles of therapy involving superovulation that resulted in a poor ovarian response and no pregnancies.
Many programs have different criteria for initiation of infertility care as well as different thresholds for cancellation. When comparing success rates among clinics, make sure the figures are comparable.
2007 Pregnancy Success Rates
Fresh Embryos from Non-Donor Eggs
| Success rates by age of woman | Under 35 | 35 – 37 | 38 – 40 | 41 – 42 |
| Number of Cycles | 96 | 71 | 40 | 16 |
| Cycles Resulting in Live Births | 36.5 % | 29.6 % | 25 % | 2/16 |
| Transfers Resulting in Live Births | 42.7 % | 37.5 % | 31.3% | 2/12 |
| Cancellations | 10.4 % | 16.9 % | 17.5 % | 4/16 |
| Pregnancies with Twins | 23.4 % | 21.4 % | 1/12 | 1/14 |
| Live Births Having Multiple Infants | 25.7% | 28.6% | 0/10 | 1/2 |
Frozen Embryos from Non-Donor Eggs
| Success rates by age of woman | Under 35 | 35 – 37 | 38 – 40 | 41 – 42 |
| Number of Transfers | 37 | 31 | 12 | 4 |
| Average Number of Embryos Transferred | 2.7 | 2.5 | 2.8 | 2.8 |
| Transfers resulting in live births | 29.7% | 29.0% | 4/12 | 1/4 |
Donor Eggs
| Success rates of all ages combined | Fresh Embryos | Frozen Embryos |
| Number of Transfers | 33 | 26 |
| Average Number of Embryos Transferred | 2.1 | 2.4 |
| Transfers resulting in live births | 72.7 % | 19.2% |
Duke Fertility Center statistics are currently available on the Centers for Disease Control’s Web site, as is information about interpreting infertility and in vitro fertilization success rates and the tables it publishes.
SART
What is SART? The Center for Disease Control (CDC) and the Society for Assisted Reproductive Technology (SART) have compiled statistics from multiple centers. They require data be collected in a standardized format for presentation. This data is referred to as the “SART data” by most centers.
