Fresh vs Frozen Donor Eggs
Is fresh or frozen the better choice for your family? Here's what the research really shows.
At A Glance
Is fresh donor egg IVF better than frozen?
Fresh eggs show somewhat higher live birth rates in several studies, but the gap narrows considerably at transfer, and shrinks further when cohort sizes are similar. See Why Egg Number Matters.
Are frozen donor eggs safe?
Yes. Frozen donor eggs are an established, clinically accepted treatment, not experimental.
How many eggs are in a typical frozen donor egg lot?
Usually six to eight. A fresh retrieval usually provides more. See Why Egg Number Matters..
Do frozen eggs have a lower fertilization rate than fresh eggs?
Not necessarily, the reported rate can be misleading. See Why Egg Number Matters..
What is a cumulative live birth rate?
The chance of at least one live birth across multiple transfer attempts from the original egg cohort, during the period a study tracked outcomes. See What Newer Studies Show.
Why Egg Number Matters
Almost every fresh-versus-frozen comparison you'll find online reports outcomes per embryo transfer. That's a real, useful number, but it only counts cycles that made it that far. It doesn't tell you how many eggs you started with, how many became embryos, or how many chances you had along the way.
A frozen donor-egg lot usually comes in a cohort of six to eight eggs. A fresh retrieval usually provides more, often quite a bit more. (Throughout this page, we use "cohort" to mean the full group of eggs you start with, before any are lost along the way.) Not every egg makes it through treatment. Some don't survive being thawed, some don't fertilize successfully, and not every fertilized egg develops into an embryo suitable for transfer or cryopreservation. So the number you start with matters, because it shrinks at each step.
One large study (Whynott et al., 2022) shows how much it shrinks for each path. Families using fresh donor eggs started with an average of 21 eggs. About 12 of those fertilized successfully. In fresh cycles, an average of 4.6 surplus embryos were cryopreserved after the initial transfer. Families using frozen donor eggs started with a much smaller group, about 7 eggs on average. About 5 of those fertilized, and an average of 1.2 surplus embryos were cryopreserved afterward. The study didn't report the total number of blastocysts formed, only what was left over after the first transfer.
One number in this data is worth pausing on, because it's easy to misread. The reported fertilization rate was actually higher for frozen eggs (69.1%) than fresh eggs (54.7%). That might look like frozen eggs fertilize better. This study can't actually establish that, because the fresh and frozen fertilization rates were calculated from different starting populations. The fresh-egg rate was calculated using every egg retrieved, including immature eggs that were never going to fertilize. The frozen-egg rate only counted eggs already selected as mature before freezing. The two groups also weren't treated identically. Nearly every frozen-egg cycle used ICSI, a fertilization technique, for all mature eggs; only 78% of fresh cycles did. Once you look at the actual numbers instead of the percentage, the picture flips. Fresh cycles produced 11.6 fertilized eggs on average. Frozen cycles produced 4.9. The reported rate was lower for fresh eggs; the number of fertilized eggs produced was not.
What Happens Once an Embryo Reaches Transfer?
The numbers above only tell you what happens before a transfer. They don't yet tell you how often a transfer actually leads to a baby.
One of the largest detailed U.S. registry analyses comes from Braun and colleagues (2024), who analyzed over 48,000 donor-egg embryo transfers nationally. One of their clearest findings involves frozen embryo transfers, or FETs: cases where the embryo itself was frozen and later transferred, regardless of whether the original egg was fresh or previously frozen. Comparing FET with FET removes the difference between fresh and frozen embryo transfer, allowing the study to examine egg origin within the same broad transfer pathway. Other differences between the groups, such as donor selection, sperm factors, or laboratory practices, may still remain:
What Newer Studies Show
A smaller, more recent study adds a useful data point, though it answers a narrower question than it might first appear to. In 2025, researchers at a single fertility center reported outcomes from 214 patients treated between 2018 and 2023. One group received an average of 8.5 mature fresh donor eggs; the other received 7.1 mature frozen donor eggs. Worth noting upfront: this wasn't a comparison between a full fresh retrieval and a small frozen lot. The two groups started with fairly similar numbers of eggs.
With similar starting numbers, the outcomes looked similar too. Fresh cycles produced an average of 5.1 blastocysts, the embryo stage typically used for transfer or freezing, compared with 3.8 for frozen cycles. Counting the transfers reported in the study, live birth occurred in 69.6% of fresh-egg patients and 66.6% of frozen-egg patients. Neither difference reached statistical significance.
That doesn't prove the two approaches are equivalent. It means this particular study, at this size, didn't find a difference large enough to rule out chance. A larger study might identify a smaller, real difference that this study was not equipped to detect.
A second, larger 2026 study of 507 patients is also relevant, with an important catch. It compared two different treatment paths rather than isolating egg origin alone: one group received fresh eggs but had their embryos frozen and transferred later, while the other received frozen eggs but had embryos transferred fresh. Cumulative live birth was 58.9% for the first group and 56.7% for the second, with no statistically significant difference. Because two things changed between groups at once, the egg's origin and whether the embryo itself was frozen, this study cannot isolate the effect of egg freezing alone. It does suggest that both complete treatment paths produced broadly similar outcomes under the conditions studied.
Taken together, these newer studies suggest that modern frozen donor eggs can perform very well, especially when fresh and frozen groups begin with similar numbers of mature eggs. What doesn't disappear is the difference in the number of eggs families commonly receive: a small frozen egg lot may produce no embryo, one embryo, or several, while a full fresh retrieval often begins with more eggs and may leave a family with more embryos available for additional attempts or future siblings. ASRM's own practice guidelines support this directly: as the number of donor eggs used increases, cumulative live birth rate tends to increase too (Strength of Evidence B, Strength of Recommendation: Moderate). The advantage of fresh donation may therefore be less about the success of any individual transferred embryo, and more about the number of opportunities created from one donor cycle.
Studies Referenced
What the Evidence Does Not Prove
These studies do not prove that every fresh donor cycle will produce more usable embryos than every frozen donor-egg lot. They also do not prove that freezing alone causes the differences seen in national registry studies.
Fresh and frozen treatment groups often differ in the number of eggs provided, donor selection, laboratory protocols, transfer practices, and the way outcomes are reported. Smaller studies from experienced centers may show very similar results when patients receive comparable numbers of mature eggs, but those findings do not establish that every clinic or egg bank will achieve the same outcomes.
The evidence also does not show that similar live-birth rates per transfer mean that the two options provide the same total family-building opportunity. A transfer rate includes only cycles that produced an embryo for transfer. It does not show how many frozen lots produced no transferable embryo, how many embryos remained for another attempt, or whether additional eggs had to be purchased.
The most supportable conclusion is narrower: modern frozen donor eggs can perform very well, particularly in experienced laboratories, while a larger fresh cohort may provide more embryos and more opportunities from one donor cycle.
What This Means
Frozen donor eggs are an established and effective treatment option. When similar numbers of mature fresh and frozen eggs are compared, recent studies suggest that laboratory and live-birth outcomes may be quite close.
The practical difference is often the number of eggs available at the beginning. A small frozen lot may produce no transferable embryo, one embryo, or several. A full fresh retrieval often provides a larger starting cohort and may therefore create more opportunities for additional transfers or future siblings.
The advantage of fresh donation may be less about whether an individual transferred embryo can succeed and more about how many opportunities one donor cycle creates.
If you're weighing this decision for your own family, you can view current donor profiles or explore our full egg donation education library for related articles as they're published.
Sunday Crider, PhD, HCLD/ELD (ABB)
Embryologist and IVF laboratory director.
Founder of The Donor Consultant.
References
Whynott RM, Summers KM, Ball GD, Van Voorhis BJ, Sparks A. Fresh embryo transfer after in vitro insemination of fresh vs. cryopreserved anonymous donor oocytes. Fertil Steril. 2022;117(4):803–810. View on PubMed
Braun CB, DeSantis CE, Lee JC, Kissin DM, Kawwass JF. Trends and outcomes of fresh and frozen donor oocyte cycles in the United States. Fertil Steril. 2024;122(5):844–855. View on PubMed
Kostoglou K, Michos G, Najdecki R, et al. Comparison of cumulative live birth rates between fresh and vitrified donor oocytes. Cureus. 2025;17(4):e82589. View on PubMed
Zhang S, Dong S, Yu Y, et al. Comparison of live birth and perinatal outcomes between fresh oocyte donation followed by frozen embryo transfer and frozen oocyte donation with fresh embryo transfer. J Gynecol Obstet Hum Reprod. 2026;55(5):103159. View on PubMed
Practice Committee of the American Society for Reproductive Medicine. Evidence-based outcomes after oocyte cryopreservation for donor oocyte in vitro fertilization and planned oocyte cryopreservation: a guideline. Fertil Steril. 2021;116(1):36–47. View on ASRM.org