How Many Donor Eggs Do I Actually Need? What the Science Says

This is one of the most common questions intended parents ask, and one of the hardest to get a straight answer to. Below, we break down the published research combined with our program statistics to help you understand how many donor eggs you should plan for based on your family-building goals.

What the research says

This 2024 study analyzed 2,660 IVF-PGT-A treatment cycles, the largest dataset of its kind, to determine how many eggs are needed by age to obtain at least one euploid embryo.¹

Average number of mature eggs needed to reach one chromosomally normal (euploid) embryo, by the age of the woman providing the eggs, from 2,660 IVF cycles with PGT-A. Egg donors fall in the under-35 row.¹

How donor eggs change the math

The numbers tell a powerful story about why using a younger donor matters: at 42, you might require ~23 of your own eggs to produce a single chromosomally normal embryo, while that same result can typically be achieved with just ~4 eggs from a donor under 35.

Donors are also screened for high ovarian reserve, meaning they typically produce more eggs per retrieval, on top of a higher share being chromosomally normal.

How many donor eggs should I purchase?

It depends on how many kids you're hoping for. Here's a rough breakdown by family goal:

These goal-based numbers are our own recommendation, not something the study states directly. They're built on the study's per-embryo average for donors under 35 (~4 eggs) plus a buffer, since fertilization and embryo development don't succeed every time. Our own program outcomes show similar egg-to-embryo ratios.

Why plan above the study's average? An average describes a hundred families at once, and outcomes at small numbers are lumpy, so one cohort might produce four chromosomally normal embryos while another produces none, and the average of the two describes neither. The ~4 egg figure is a midpoint rather than a safe margin, which is why we suggest planning on closer to 5 to 6 eggs for each chromosomally normal embryo you hope to end up with. If you want two children from the same donor, plan for two normal embryos from the start rather than counting on returning to her later.

If you would prefer the option to choose your baby's sex, you'll want to aim for roughly double your target embryo goal.  

What our program outcomes tell us

The research above gives us a strong benchmark,  and it lines up closely with our own tracked outcomes since 2012.

Fresh Matching Program outcomes

Across Fresh Matching cycles from 2012 to 2025, our donors have averaged:

28.9 eggs retrieved → 22.6 mature → 18.2 fertilized → 7.2 euploid embryos²

That's about 3 mature eggs per euploid embryo, right in line with the research, if not a bit more efficient.

Frozen Egg Bank outcomes

Our Frozen Egg Bank cohorts are built around this same data: a standard lot is 6 eggs. In practice, standard lots from 2012 to 2025 have produced at least one blastocyst for 81.1% of patients, and two or more for 60.5%. Across completed cohorts, it takes about 3.8 warmed eggs to reach one chromosomally normal embryo, a little more than the roughly 3 mature eggs in Fresh Matching, since about 9 in 100 frozen eggs don’t survive warming.²

Every cohort comes with a Blastocyst Embryo Guarantee: at least one blastocyst by day 7. One distinction to keep in mind: a blastocyst isn't automatically a euploid embryo. The two are confirmed separately, and only PGT-A testing can confirm the latter. 

Also important to note: you're not locked into buying in fixed increments of six. If your selected donor has extra eggs available, you can often purchase more than a standard cohort. (More on how that works in the FAQ below.)

Why more than one embryo often makes sense

A chromosomally normal embryo doesn't guarantee a pregnancy on the first try, which is why most intended parents plan beyond the bare minimum, especially if they want more than one child.

Trying again with a second or third embryo raises your overall odds substantially, even though no single attempt is guaranteed. Another study shows implantation rates were 69.4% on the first transfer, 59.3% on the second transfer, and 59.2% on the third transfer, but the cumulative pregnancy rate reached 94.9% by the third attempt.³

What this means for your family-building goals

One child, using a donor under 35? A standard 6-egg cohort is a solid research-backed starting point.

More than one child? Fresh Matching is usually more efficient, since you get all mature eggs from that one retrieval.

Using your own eggs, 38 or older? This is typically where the math starts favoring donor eggs.

Ready to take the first step?

Explore detailed donor profiles on our online database, and when you want a second opinion on the numbers, your dedicated case manager can walk through what makes sense for your goals and budget in a free consultation.

Frequently asked questions about how many donor eggs you need

How many eggs do I need for IVF?

It depends on the age of the eggs and how many children you hope to have. With a donor under 35, it takes about 4 to 5 mature eggs on average to reach one chromosomally normal embryo, so we suggest planning on about 6 donor eggs per child. With your own eggs, the average rises to about 12 to 13 at 40, 22 to 23 at 42 and 39 to 40 at 43. The table above shows every age group.¹

How many frozen donor eggs do I need for one normal embryo?

About 3.8 warmed eggs on average, based on Donor Nexus Frozen Egg Bank outcomes, compared with about 3 mature eggs in Fresh Matching. Averages understate how often a small cohort comes up short, so we suggest planning on 5 to 6 frozen eggs for each chromosomally normal embryo you hope to have. A standard lot is six eggs, and about 4 in 5 patients get at least one blastocyst from one.²

Do donor eggs really lead to higher success rates?

Yes. Per SART's 2023 National Summary Report, a woman using her own eggs over 42 has a 4.1% live birth rate per retrieval. With donor eggs, that rises to 37.9–46.6%. Two compounding factors drive this: donor eggs are more likely to be chromosomally normal individually, and donor cycles also typically retrieve more eggs overall, both of which stack in favor of a successful outcome.⁴

Can I use the Frozen Egg Bank for more than one child?

Yes. A standard cohort is six eggs, but you're not limited to increments of six. If your donor has extra eggs available, you can purchase more. If she doesn't have enough, we can ask if she's open to cycling again, or help you find eggs from a second donor. For three or more children, Fresh Matching is usually more efficient.

How many euploid embryo transfers until success?

Research presented by RMA/IVIRMA at the 2019 ASRM annual meeting tracked 4,515 patients through up to three consecutive single euploid embryo transfers. Per-transfer implantation rates were 69.4%, 59.3%, and 59.2%, but cumulative pregnancy rate hit 94.9% by the third attempt.³

What's the difference between a blastocyst and a euploid blastocyst?

A blastocyst is an embryo that's reached a developmental stage, typically day 5–7, splitting into two cell types that become the fetus and placenta. Euploid means it has the right number of chromosomes. These aren't the same thing: a well-developed blastocyst can still test chromosomally abnormal. The two get linked in practice because PGT-A requires a biopsy, only safe once an embryo reaches blastocyst stage.

In our Fresh Matching cycles, about 6 in 10 blastocysts test chromosomally normal. In our Frozen Egg Bank, about 4 in 5 patients get at least one blastocyst, while among the cohorts that went on to chromosomal testing, closer to 3 in 5 produced at least one normal embryo.² So when a program quotes a success rate, ask two things: whether it counts blastocysts or chromosomally normal embryos, and whether it is measured per cohort, per warming, per transfer or per patient, since those are four different numbers.

How many donor eggs are retrieved in a typical cycle, and how many fertilize?

At Donor Nexus, Fresh Matching donors average 28.9 retrieved, 22.6 mature, and 18.2 fertilized (about 80%). Our Frozen Egg Bank sees 83.1% fertilization after thaw, both notably higher than general clinical benchmarks (Cambridge NHS cites ~60% fertilization for frozen donor eggs).²⁵

Sources

1. Rodríguez-Varela C, et al. Fertility and Sterility. 2024;122(4):658-666. DOI: 10.1016/j.fertnstert.2024.06.002
2. Donor Nexus program outcomes, Fresh Matching and Frozen Egg Bank cycles, 2012 to 2026.
3. Reproductive Medicine Associates (RMA/IVIRMA). Women with three normal embryos have a 95% chance of pregnancy. Research presented at the ASRM Scientific Congress, 2019.
4. Society for Assisted Reproductive Technology. 2023 National Summary Report.
5. Cambridge University Hospitals NHS Foundation Trust. Use of donor eggs: information for patients.

Related reading

Should You Use Fresh or Frozen Donor Eggs?Cost, timeline, sibling planning and logistics compared side by side.Compare your optionsDonor Egg IVF Success RatesWhat the published numbers measure and how to compare them between programs.See the numbersWhat Happens After IVF Fails?Grief, next steps and how one mom decided donor eggs were her way forward.Read her story