ERA Testing

ERA Test for IVF: What It Is and When It Helps

What does ERA in IVF mean? ERA stands for Endometrial Receptivity Analysis. The ERA test helps find the best time to transfer an embryo. This time is known as the “window of implantation.” It increases the chance of a successful pregnancy. Originally developed for women with recurrent implantation failure, ERA is now widely available as an optional add-on. But who truly benefits from this test? At Positive Steps Fertility, we use ERA thoughtfully—when it’s most likely to make a difference

What is ERA testing?

ERA stands for Endometrial Receptivity Analysis. ERA is a molecular test used during IVF to determine if the lining of the uterus—the endometrium—is ready to receive an embryo. This critical moment is called the “window of implantation.”

Originally designed for women with recurrent implantation failure, ERA has become more widely available as an optional test. Its purpose is to personalize the timing of embryo transfer to improve the chances of pregnancy.

Also known as the ERA fertility test, or endometrial receptivity assay, this analysis helps identify whether your optimal implantation window differs from the standard IVF timeline. For about 1 in 5 women, that timing may be earlier or later than expected. ERA helps ensure the embryo is transferred at the right time, when your uterus is most receptive.

Why is the ERA test done?

ERA is usually recommended after multiple failed embryo transfers. If you’ve used high-quality embryos and everything else seems right, but you’re still not pregnant, this test can help. It evaluates whether your embryo transfer is happening at the optimal time. If your endometrium isn’t receptive when the embryo is placed, implantation is unlikely to succeed.

How does ERA testing work?

ERA testing involves a mock cycle that mimics a frozen embryo transfer (FET). You’ll take estrogen for about 10 days to thicken the lining. Then, you’ll take progesterone for 6 days. On day 6 of progesterone, a small biopsy of your uterine lining is taken. The lab analyzes this sample for the activity of more than 200 genes to determine whether your uterine lining is receptive, pre-receptive, or post-receptive. Results help your doctor adjust the exact timing of your actual embryo transfer.

What are the benefits of ERA testing?

For women undergoing IVF—especially those experiencing recurrent implantation failure—the ERA test can offer clarity and direction when other tests fall short.

  • Personalized timing: Finds the ideal time for embryo transfer based on your unique biology
  • Improved outcomes: Can increase implantation rates for select patients
  • Emotional relief: Offers answers when other test results seem normal
  • Fewer failed cycles: Helps avoid mistimed embryo transfers

What is endometrial receptivity?

The uterine lining plays a key role in implantation. According to the American College of Obstetricians and Gynecologists (ACOG), estrogen thickens the lining early in the cycle. After ovulation, progesterone prepares the lining to receive an embryo. This window of implantation typically occurs 5 days after starting progesterone. For some women, this window may be earlier or later than expected.

Disruptions in this timing can make implantation less likely, even if the embryo is healthy. The ERA test helps uncover those timing issues.

At what point during IVF should women undergo ERA testing?

ERA testing is not part of every IVF cycle. It’s usually considered after one or more failed transfers with good-quality embryos—especially when no clear cause of failure is found.
Fertility specialists often recommend ERA testing in these situations:
  • After two or more failed IVF cycles with good embryos
  • When egg and sperm quality, embryo development, and uterine anatomy all seem normal
  • For women over 35 who want to avoid another failed transfer
  • When using donor eggs or embryos, where embryo quality is well-established

Some patients ask if ERA testing should be done before their first transfer. Current research suggests it’s most helpful for patients with previous failed cycles. The American Society for Reproductive Medicine (ASRM) supports its use for select patients.

Your doctor can help decide whether ERA testing could improve your IVF results.

How to prepare for an ERA test

If you’re wondering about the ERA test procedure, here’s what to expect. This test follows a timeline similar to a frozen embryo transfer cycle but ends with a biopsy instead of an embryo transfer.

  • Estrogen: Taken for about 10 days to thicken the uterine lining
  • Progesterone: Taken for 6 days. This phase controls when the lining becomes receptive
  • Biopsy: A small tissue sample is collected on day 6 of progesterone
  • Analysis: The sample is tested for over 200 genes that relate to endometrial receptivity
  • Transfer plan: Your FET protocol is then adjusted based on your personalized timing
The full ERA cycle takes about 4 weeks, including testing and results.

What does the latest research say about ERA testing?

While ERA testing may not benefit every IVF patient, it can be a valuable tool for some. A 2021 study in Fertility and Sterility showed that personalized embryo transfer based on ERA improved pregnancy rates in patients with repeated implantation failure.

The ASRM advises that ERA may be useful in certain cases, particularly when other causes of IVF failure have been ruled out.

You can also explore insights from the ACOG, which highlights how hormonal shifts shape the uterine lining. Estrogen builds the lining; progesterone makes it receptive. When this timing is off, implantation may not occur.

Are there concerns about ERA testing?

While ERA can help optimize embryo transfer timing, it’s not the right choice for everyone. Patients and providers should weigh the following considerations:
  • Cost vs. benefit: ERA is often an out-of-pocket expense and may not be covered by insurance.
  • Unclear benefit for first-time IVF patients: Most research supports ERA for patients with recurrent implantation failure—not for routine use.
  • Added stress: ERA testing adds time, complexity, and sometimes emotional burden to an already demanding IVF process.
The American Society for Reproductive Medicine (ASRM) does not recommend ERA testing as a standard screening tool but recognizes it may be helpful for certain patients. At Positive Steps, we can help you see if ERA is a good choice based on your fertility history.

When is ERA testing recommended?

ERA testing isn’t the first step in fertility treatment. It’s used when other explanations for IVF failure have been ruled out. It can be especially helpful in these scenarios for patients researching ERA in IVF:
  • After two or more failed IVF cycles using good-quality embryos
  • When no obvious issues (like egg or sperm quality) explain failed implantation
  • For women over 35 who want to avoid another unsuccessful cycle
  • For those using donor eggs or embryos where embryo quality is known

Final Thoughts from Dr. Parry

At Positive Steps, we start with the simplest answers. But when those don’t explain what’s happening, we go deeper. While not every IVF journey requires ERA testing, it can be a useful tool for patients who have experienced implantation failure that may be related to endometrial timing.

If you’re wondering whether ERA testing could help you, let’s talk. Every step forward is a positive one.

 

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