Medical Research

Is Freeze-Only Effective?

More and more frequently doctors recommend their IVF patients freeze all of their embryos before making a transfer. To the positive, the approach makes it easier to genetically-test the embryos, reduces rates of OHSS, and theoretically gives the endometrium time to recover and clinicians the chance to find the window when it's most receptive to receive the embryo.

On the other hand, freeze-only approaches are likely only as productive as the (wide variety of) laboratories handling the embryos, have been associated with "large for gestational age" offspring and likely add to the patient's total bill for that cycle.

Why This Study Was Special

Studies analyzing the value of freeze-only cycles have been extremely small in nature and performed at the hands of one or two clinicians at a single center. We just can’t say if their findings (which are supportive of freeze-only) apply to a broad group of fertility patients who will be treated at a spectrum of clinics (with varying degrees of laboratory freeze / thaw skill).

This study addresses a number of these shortcomings. It involves a large number of cycles (nearly 1,500 cycles, 3 - 10x more than we're accustomed to), performed on a broad variety of patients, treated at over 12 clinics and nicely matches the freeze-only group to a control group of patients that appear similar and who had a fresh embryo transfer.

What Was Tracked And What They Found

The investigators looked at Ongoing Pregnancy Rates (but not Live Birth Rates, a shortcoming) and found that patients who had freeze-only cycles outperformed their matched cohorts. However, the difference was only meaningful when the woman had a Progesterone level >1.0 ng/mL. At that level, or below, there was no statistical difference. It appears that within each Progesterone range, women ages 36 and above saw more benefit than women 35 and younger.

The Study’s Limitations

First, the study did not include an assessment of Live Birth Rate. Patients care about taking home a baby and so anything short of measuring this is probably incomplete. We’ve seen plenty of studies where therapies improve pregnancy rates but don’t improve actual take-home baby rates.

Second, the trial was not prospectively randomized and so we cannot be certain the groups being compared are in fact similar, or if the treatment is responsible for any difference in outcome we saw above.

Third, these patients were able to make multiple blastocysts and so what was seen may not apply to poor responders.

The Takeaway

Freeze-only is not equally helpful for all fertility patients. It's worth having a refined, data-driven discussion with your doctor about the benefits freeze-only confers and where (and for whom) it's yet to drive higher live birth rates.

You can see a more complete description of the data on fresh vs. frozen embryos here.

Related Courses

IVF - In Vitro Fertilization

Learn More
The most complex fertility treatment, this course will help you do it right the first time.

Embryo Transfer

Learn More
We cover how many embryos to transfer, medicated vs. unmedicated cycles, fresh vs. frozen, and the do's and don'ts on transfer day itself.

Lifestyle Choices, From Diet To Supplements

Learn More
All the data on lifestyle choices and their impact on fertility, including decisions around diet, exercise, drinking alcohol, caffeine consumption, smoking, recreational drugs, and using supplements.

PGT (PGS) Genetic Screening

Learn More
Giving you the full picture: where it helps, where it doesn’t, and how you might think about this expensive add-on based on your specific priorities.

The IVF Laboratory

Learn More
Lab quality determines success. This course explains how to vet a lab to give yourself the best chance of a good outcome.


Learn More
ICSI costs $3-5k but only improves birth rates in specific circumstances (hint: it’s not as simple as “helps with male factor”). We break down when it’s truly helpful.

Fertility 101

Learn More
You took sex ed, but now you need to understand fertility. Data to answer your questions about natural conception and diagnosing what might be wrong.


Learn More
Breaking down all the data and information on what endometriosis is, how to best diagnose it, and what the best treatment is depending on who you are

Egg Freezing

Learn More
Preparing you to be a confident self-advocate as you make decisions around fertility preservation.


Learn More
Does acupuncture & traditional Chinese medicine really make a difference for fertility? See the data on IVF, other fertility treatments, and trying naturally with acupuncture and Chinese herbs.

IUI or "Artificial Insemination"

Learn More
Data on IUI success rates depending on who you are, what it costs, the risks, and how to decide between doing IUI and IVF.

Male Factor Infertility

Learn More
Male factor infertility impacts anywhere between a third and half of a couple's difficulty in conceiving. The primary factors often end up being related to varicocele or some form of azoospermia. While a semen analysis can help characterize if there is an issue, the test can be inconsistent, difficult to interpret.

Surrogacy For Gay Dads: An Introduction

Learn More
Introducing the major decisions a gay couple or single man need to make to become fathers. We cover the costs of everyone involved, an intro to finding an egg donor & surrogate or gestational carrier, how state laws differ for gay and single dads, pros and con of twins, and finding a clinic as a gay or single man.
Related Lessons

Freezing Eggs vs. Embryos

Transferring Fresh or Frozen Embryos

Frozen Embryo Transfer: Different Options To Prepare the Endometrium

Growing Embryos To Cleavage or Blastocyst Stage

Which Embryo To Transfer?


Body Fat and Fertility

BPA, Toxins, Pesticide and Phthalate Exposure

Choosing a Clinic as a Single or Gay Dad

Conception: How Pregnancy Happens

Conventional Insemination or ICSI

Costs of IVF

Deciding Between IUI vs IVF

Diagnosing Endometriosis

Diagnosing Fertility Issues & Getting Help

Dietary Patterns and Fertility

Does Acupuncture Improve Outcomes?

Does Egg Freezing Work?

Exercise and Fertility

Fertility Impacts of Carbohydrates, Dairy, Meat, Fish, Soy & More

Getting Pregnant Naturally

Herbs and Fertility

How Does Acupuncture Theoretically Address Fertility Challenges?

How Fertility Treatments Address Our Problems

How Many Embryos to Transfer?

How State Laws Differ for Single & Gay Dads

How Well IUI Works By Patient Type

How You Can Measure Lab Quality?

Improving Your Live Birth Rate Per Transfer

Issues That Prevent Pregnancy

IVF, ICSI, IUI & Male Factor Infertility

IVF Success Rates

Knowing Whether You Should Freeze Eggs: Predicting Whether You’ll Have Trouble Conceiving

Lifestyle Factors & Their Impact on Male Factor Infertility

Men Finding Egg Donors

Older Dads

Ovarian Stimulation Protocols

Overview: Men Having Babies

PGT-A and PGS Genetic Screening of Embryos

Reproductive Endocrinologists & Urologists

Risks of IVF

Smoking, Caffeine, Alcohol: Impacts On Fertility

What is IVF?

Testosterone, Hormone Imbalances, and Male Factor Infertility

The Age When You Freeze: Understanding the Implications and Tradeoffs

The Benefits of PGS

The Biggest Decisions In An IUI Cycle

The Importance of The Laboratory

The Semen Analysis

Treating Endometriosis


Vitamins, Supplements & Fertility

What Is Endometriosis?

What Is PGS?

What Is Mosaicism And Why Should I Care?