Fresh vs. Frozen Embryo Transfer: What’s the Difference?

If you’re researching IVF or are already in a cycle, you might have heard of embryo transfer.

This stage is where the embryos grown in the lab are transferred to a flexible tube and inserted into their new home, your uterus.

But did you know there are two ways to do this?

One method is shorter and involves egg retrieval, growing embryos in the lab, and transferring them, in one, single cycle.

The second method is longer and involves embryo freezing and transfer at a later date (side note: this is not the same as egg freezing, which is when you freeze mature eggs that have been retrieved from your ovaries before they are fertilized).

So let's do a deep dive into these terms, how they’re done, the success rates and answer some common questions on the big debate: Which is better, fresh or frozen transfer?

In this article: 📝

What's the difference between fresh vs. frozen embryo transfer?

Let's start with the essentials.

Embryo transfer is the process where an embryo is prepared for transfer from a lab-based culture to a more natural environment (your uterus).

Both processes start with the same stage: egg retrieval.

Let's take a peek at the timeline.

So on day 1, the eggs are retrieved from the follicles, and fertilized with sperm.

The embryo is then grown until day 5 or 6 in tiny glass dishes, filled with nutrient media, then graded.

After this stage is where the fresh vs. frozen differences start.

In a fresh embryo transfer, the embryos are transferred to the uterus in the same cycle (usually on day 5).

This makes the procedure short, and the cycle completes in about a week.

For frozen embryo transfer (often abbreviated to FET), the embryo is frozen on day 3 or day 5-6.

This makes the procedure longer, and this embryo can then be transferred weeks, months, or even years later.

Which is better, fresh or frozen embryo transfer?

There’s no single ranking factor to decide which procedure is better.

There are several factors to consider, like medical history, stimulation cycle, or hormonal levels, all of which are considered before you are directed toward a cycle.

But you might be directed toward a fresh embryo transfer if you have:

• Optimal endometrial thickness: The inner layer of the uterine cavity is called “receptive” to the embryo if it's around 7-14mm. This is an ideal range and helps house the growing embryos.

• No previously failed fresh cycles: You may be a candidate for fresh transfer if your hormonal levels are optimal, and if you have no previously failed fresh IVF cycles.

  Or a frozen embryo transfer might be recommended if you have:

• Been advised to carry out genetic testing: Genetic testing of embryos is usually done on samples obtained from day 5 embryos. They extract the sample and then freeze the embryos as the reports take anywhere from a week to a month to arrive.

• Surplus embryos: If the number of embryos retrieved is more than 2-4, the rest of the embryos are frozen.

• Non-optimal endometrial thickness: In the same cycle, if your endometrial thickness is less than 7mm or greater than 14mm, you may be directed to a frozen embryo transfer cycle.

• Previously failed fresh cycles: If your history includes fresh cycles that didn't work out in the past.

• Non-optimal hormonal levels: In the same cycle, if you have non-optimal hormonal levels on day 5 or 6, you may be directed towards a frozen transfer. This helps doctors either medicate or naturally wait for your body to return to normal hormonal levels. After that, the embryo transfer is planned for a later date.

Success rates for fresh vs. frozen embryo transfer

There's a lot of information and medical studies out there comparing fresh and frozen transfers.

But it's important to know that data on IVF success rates isn't a direct correlation to how your cycle may turn out.

If you are after more info, here are a few key studies to check out:

• This study from 2016 compared the outcomes of fresh and frozen transfers and found no differences in parameters such as biochemical pregnancy rates, gestational sac, and fetal heart activity.
• This study in 2019, favors frozen embryo transfers as they have a higher live birth rate (especially for those with PCOS) and lower frequency of pregnancy loss.
• In another study from 2015, fresh transfers were done for patients who had optimal hormonal levels. It was still found that the frozen transfers performed better. This shows that the endometrial thickness plays a major role. In fresh cycles, the endometrium can be affected by the medications given for egg retrieval. In the case of frozen cycles, the endometrium has a chance to be primed better, as there’s a longer gap between retrieval and transfer.
  There are several studies that compare the two and indicate that frozen embryo transfer is better.

But, ultimately, it comes down to choosing the one that’s best for you and your fertility journey.

It is, after all, your choice.

How much are fresh vs. frozen embryo transfers?

In terms of cost, a frozen embryo transfer on average costs around $3,000 to $5,000 in the US and between £880 to £2,000 in the UK.

For a fresh embryo transfer, you're looking at around $12,000 to $14,000 in the US and around £2,500 to £4,500 in the UK, although these costs generally include your appointments, egg retrieval, embryo creation, and your fresh embryo transfer.

Some insurance companies can help with the cost of fertility treatments like IVF, and fresh or frozen embryo transfers, so it's worth checking with your provider before making a decision.

And if you choose to have more than one cycle, there are ways to reduce the costs.

Is IVF cheaper if you already have frozen embryos?

Yes, using frozen embryos from a previous cycle is cheaper than a complete IVF fresh cycle from scratch.

The physical and emotional stress is also lesser, as the cycle is shortened.

The procedures include egg retrieval, IVF, embryo freezing, and finally transfer which on their own, are less compared to a total IVF package.

What are the pros and cons of fresh and frozen embryo transfers?

Well, everyone's fertility journey is unique, so what might be a 'pro' to one person could be a 'con' to another.

But here are some of the pros and cons of both fresh and frozen embryo transfers:

Fresh embryo transfer

Pros:

• Timing advantage: Fresh transfers sync with your natural cycle, potentially leading to more favorable conditions for implantation.
• Immediate use: No freezing and thawing process – embryos are transferred right away.
• Single cycle: If all goes well, you can have a single cycle from stimulation to transfer.

Cons:

• Stressful timing: There's a very specific timeline to follow for fresh embryo transfers, with not much of a window for flexibility.
• OHSS risk: Ovarian Hyperstimulation Syndrome (OHSS) risk due to hormonal stimulation, particularly if you undergo several egg retrievals.

Frozen embryo transfer

Pros:

• More flexible timing: Embryos are frozen and thawed for transfer, allowing for better timing and conditions.
• Reduced OHSS risk: The risk of OHSS is greatly reduced as it mostly occurs during fresh stimulation.

Cons:

• Wait time: Embryos need to be frozen and thawed, leading to a longer timeline.
• Impact of multiple cycles: If embryos aren't successful in the first transfer, you might need multiple cycles, which can be costly and stressful.
• Cost of storing frozen embryos: Another cost to consider with frozen embryo transfers.

Which should I choose: fresh or frozen embryo transfer?

There's no "right" answer to this.

Ultimately, your IVF journey is unique and is influenced by many factors: your age, the clinic, your hormone levels, medical history, and so on.

And, it's important to remember that talking your options through with your doctor is the best way to go ahead with your cycle, or if you’re planning for IVF.

They can provide you with the right information that works best for your cycle and has the potential to boost success rates.

Whatever you decide will be the right choice for you.