The Headline Numbers

The number most people land on first is the live birth rate per cycle, grouped by the age of the person providing eggs. SART's 2021 data gives us national averages for live birth per intended egg retrieval:

  • Under 35: 54.4%
  • 35 to 37: 41.1%
  • 38 to 40: 26.7%
  • 41 to 42: 13.8%
  • Over 42: 4.3%

One important detail: these figures capture the cumulative chance of a live birth from all embryos created in a single retrieval, including any frozen embryo transfers that happen afterward. They are not per-transfer rates.

Why Clinic-Reported Rates Vary So Much

You will see one clinic advertising 65% success and another sitting at 45%, and it is tempting to assume the higher number means better care. In practice, the gap usually comes down to who each clinic chooses to treat. A center that takes on only straightforward cases with good prognosis will report higher numbers than one that regularly accepts patients other clinics have declined.

A few other variables shape the numbers you see:

  • Single vs. multiple embryo transfer: Transferring two embryos pushes the per-transfer pregnancy rate up, but it also raises the odds of twins, preterm birth, and NICU stays. Clinics that commit to single embryo transfer (eSET) may show slightly lower pregnancy rates while delivering better outcomes per baby.
  • Fresh vs. frozen transfer: Frozen embryo transfers (FET) have closed the gap with fresh transfers and sometimes exceed them, partly because the uterine environment is more controlled. A clinic that freezes everything will report differently than one doing mostly fresh transfers.
  • PGT-A testing: Embryos that pass genetic testing carry per-transfer rates of 60% to 65% regardless of the age at retrieval. But fewer embryos survive the testing process, and the per-retrieval rate accounts for that loss.

What Actually Predicts Your Outcome

Your own odds hinge on a small set of measurable factors:

  • Age: The single strongest predictor. Egg quality declines with age, and no protocol can reverse that.
  • AMH (anti-Mullerian hormone): A rough gauge of how many eggs you are likely to retrieve. Higher AMH generally means more eggs, more embryos, more chances per retrieval.
  • Antral follicle count (AFC): The number of small follicles visible on a baseline ultrasound. It tracks with AMH and retrieval yield.
  • Previous response: If this is not your first cycle, how your body responded to stimulation before is one of the best predictors of how it will respond now.
  • Sperm quality: Severe male factor, very low count, motility, or morphology, can drag down fertilization rates even with ICSI.
  • Uterine factors: Polyps, fibroids, or adenomyosis can lower implantation rates. The good news is these are often treatable before transfer.

How to Use SART Data

The SART website (sart.org) lets you pull up individual clinic results. When you are comparing options, focus on:

  • Live birth rate per intended egg retrieval (the most honest metric available)
  • Number of cycles reported (a larger sample gives you more reliable data)
  • Percentage of eSET (single embryo transfer, a marker of responsible practice)
  • Cancellation rate (a very low rate might signal that the clinic cherry-picks easy cases)

Steer clear of pregnancy rates, which include biochemical pregnancies and miscarriages, and per-transfer rates, which exclude cancelled transfers and failed fertilizations.

The Emotional Math

A 40% success rate means a 60% chance the first attempt will not work. Think of it as a coin flip with slightly worse odds. After two cycles, your cumulative chance climbs to roughly 64%. After three, about 78%. IVF is often a multi-cycle commitment, not a one-shot procedure.

Doing the math is one thing. Sitting with those numbers is another. A percentage cannot capture how it feels to be on either side of the line. If the data feels heavy right now, our guide on IVF and mental health walks through strategies for carrying that emotional weight.

Next Steps

Ready to take the next step? Search for fertility specialists in the Baaby provider directory, or browse our IVF guides for details on medications, costs, and the two-week wait.