Survey examines the use and attitude of natural cycle FETs in US clinics

Researchers in a 2023 study share the results of a survey that evaluates the use and attitude of natural cycle FETs in US clinics, which some studies have recently shown can lead to improved pregnancy outcomes compared to medicated FETs.

Recent data has shown that natural cycle frozen embryo transfers (NC-FETs) may lead to better pregnancy and obstetric outcomes compared to medicated FETs, possibly due to differences in hormone levels and endometrial development.

Check out my post on the different FET protocols to learn more about them and the data that shows improved outcomes using NC-FETs.

Lee et al. (2023) conducted a survey to evaluate NC-FETs in the US, including their current utilization rates, protocols, restrictions, and perspectives.

They sent a survey to 441 US clinics and 216 (49%) responded, of which 179 (83%) reported offering NC-FETs.

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A closer look at clinics that do not offer natural cycle FETs

From the survey, 17% of clinics don’t offer NC-FETs.

Of the clinics that don’t offer NC-FETs:

• Most were private (84%).
• Most had 1-2 physicians (65%).
• Most had 500 or fewer cycles a year (48%).

The top 3 reasons for not offering NC-FETs were:

1. Lack of timing predictability for transfer.
2. Increased burden on staff/lab personnel on holidays and weekends.
3. Inability to coordinate provider/patient schedule for transfer.

A closer look at clinics that do offer natural cycle FETs

Of the clinics that do offer NC-FETs:

• Most were private (56%).
• Most had 3-5 physicians (43%).
• Most had 1000+ cycles a year (27%).

Despite offering them, NC-FETs make up 25% or less of FET cycles (75% of clinics).

Some clinics have restrictions for NC-FETs:

• 52% of clinics had restrictions.
• 64% of clinics had restrictions because of irregular ovulation/anovulation.
• Other restriction include diminished ovarian reserve/primary ovarian insufficiency (6%), adequate endometrium (8%), age <40 (8%) and previous failure with medicated cycles (4%).
• 63% of clinics allow NC-FETs in anovulatory women, with most (61%) using letrozole or letrozole and clomid (25%) for ovulation induction. Note: If using ovulation induction, this is a “mildly stimulated FET,” which is essentially a NC-FET with mild ovarian stimulation to induce follicle development/ovulation. I describe the different FET types in my post Comparing frozen embryo transfer/FET protocols.

For clinics that offer NC-FETs, the top 3 benefits reported were:

1. Patient satisfaction.
2. Decreased cost of medications.
3. Avoidance of intramuscular progesterone.

For clinics that offer NC-FETs, the top 3 negatives reported were:

1. Lack of timing predictability for transfer.
2. Increased burden on staff/lab personnel.
3. Inability to coordinate provider/patient schedule.

About 20% of clinics report that there is “limited data regarding chance of success” with NC-FETs, suggesting that some doctors aren’t convinced by the existing evidence and more research needs to be done.

Most clinics (63%) believe that NC-FETs have increased at their clinic in the last 5 years.

Clinic attitudes on natural cycle FETs

Most clinics (51%) have a positive attitude toward NC-FETs, with 14% having a negative attitude. The main barrier for NC-FETs was indicated as logistics/scheduling with 56% of clinics.

With new research coming out that shows benefits for NC-FETs, 45% of physicians have indicated that this has changed their attitude in favor of the method.

Nearly 70% of physicians report that there hasn’t been an increase in patient demand for NC-FETs, indicating that patients may not be aware of the benefit.

Conclusions

In general, clinics with more physicians and higher volume were more likely to offer NC-FETs.

While clinics may offer NC-FETs, these cycles make up a minority of total FET cycles (25% or less). The authors point to studies in China and Sweden that show that they perform NC-FETs at a higher rate of 49-68%.

About half of clinics had restrictions on offering NC-FETs, with the most common reason being irregular ovulation/anovulation. The authors state that this could potentially exclude many patients, and cites 2019 CDC data showing that 13.9% of patients have ovulatory dysfunction. Ovulation induction using letrozole, or other medications, may help these patients.

Of the 17% of clinics that don’t offer NC-FETs, most report that this relates to logistic/scheduling concerns.

About 20% of clinics report that there is “limited data regarding chance of success” with NC-FETs, highlighting the need for more research, in particular well-designed randomized controlled trials. Currently most of the data is retrospective.

“If embryo transfer in a natural cycle is further proven to benefit obstetric and neonatal outcomes, clinics will be challenged to address the most common barriers to offering NC-FET described in [our] study.”

Lee et al. (2023)

Reference

Lee JC, Calzada-Jorge NS, Hipp HS, Kawwass JF. Natural cycle frozen embryo transfer: a survey of current assisted reproductive technology practices in the U.S. J Assist Reprod Genet. 2023 Apr;40(4):891-899. doi: 10.1007/s10815-023-02751-w. Epub 2023 Mar 1. PMID: 36856966; PMCID: PMC10224901.

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About Embryoman

Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.

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