Frozen vs. Fresh Embryo Transfer: How US Clinics Practice Today

Not long ago, most IVF embryo transfers in the US happened a few days after egg retrieval, using “fresh” embryos. Today the CDC data shows the opposite: the large majority of transfers use embryos that were frozen first and thawed later.^[1] This guide shows how far that shift has gone, how much clinics differ, and what the data can and cannot say about outcomes.

Fresh and frozen transfers in brief

In a fresh transfer, an embryo created in the lab is placed in the uterus in the same cycle as the egg retrieval, usually a few days later. In a frozen transfer, embryos are cryopreserved (vitrified) and transferred in a later cycle, after the uterus has been prepared with or without medication.^[3] Freezing also lets patients store extra embryos for later attempts.

How common are frozen transfers?

In 2022, 86.9% of all embryo transfers reported to the CDC used frozen embryos.^[1] The share has risen every year in the last three CDC reporting years:^[1][2]

Year	Transfers using frozen embryos	Total ART cycles
2020	81.6%	326,471
2021	83.8%	413,776
2022	86.9%	435,426

The pattern holds across age groups:^[1]

Age group	Transfers using frozen embryos (2022)
Under 35	86.8%
35–37	88.8%
38–40	87.9%
Over 40	83.4%

Why clinics freeze embryos

Clinics give several reasons for freezing embryos rather than transferring them fresh. Freezing allows time for genetic testing of embryos (PGT), which requires a biopsy and lab results before transfer. It lets the body recover from ovarian stimulation before pregnancy, and it makes it possible to bank embryos from several retrievals. Rising PGT use and rising frozen transfers have moved together in the CDC data. See how often clinics use PGT.

The CDC data records what clinics did, not why. Whether a frozen or fresh transfer is better for a specific patient is a medical question to discuss with a clinician.

How much clinics differ

Clinic practice varies a lot. Among 438 clinics with data, the median clinic used frozen embryos in 91.8% of transfers, and the middle half of clinics ranged from 79.6% to 97.7%.^[1] 178 clinics used frozen embryos in 95% or more of transfers, while 14 used them in fewer than half.^[1]

States with at least five reporting clinics, ranked by the median clinic’s share of frozen transfers:^[1]

State	Median clinic: frozen transfers	Clinics with data
Arizona	98.3%	10
Nevada	98.1%	6
Hawaii	98.0%	5
Kansas	98.0%	5
California	96.1%	79
Colorado	95.9%	7
Tennessee	95.9%	7
Texas	94.7%	44
…
New Jersey	82.9%	13
Maryland	82.5%	5
Washington	82.0%	12
Indiana	73.8%	7
Massachusetts	69.6%	8

Each clinic page on FertilityList shows that clinic’s share of frozen transfers next to the national figure, in the “Practice patterns” table.

How do outcomes compare?

The CDC’s main own-egg success measures are cumulative. They count live births from all transfers, fresh and frozen, within a year of a retrieval, so they do not split results by transfer type.^[4] For donor eggs, the CDC does report by type. In 2022, frozen embryos created from donor eggs had a live-birth rate of 45.1% per transfer, compared with 52.0% for fresh embryos from fresh donor eggs.^[1] The frozen group was far larger (18,678 transfers versus 791).

These groups differ in ways the data does not capture, such as patient selection and whether embryos were genetically tested. So the numbers do not show that one approach is better. Research on this question is ongoing, and practice guidance changes over time.

Single-embryo transfer and freezing

Freezing also supports transferring one embryo at a time while storing the rest. Transferring a single embryo lowers the chance of twins or triplets, which carry higher health risks for parent and babies. With good freezing techniques, extra embryos remain available for later attempts. The CDC reports singleton and multiple births separately for each clinic. Ask your clinic about its multiple-birth rate and how many embryos it usually transfers.

What this means when comparing clinics

• Per-transfer rates depend on practice. A clinic that freezes and tests most embryos may transfer fewer, more selected embryos, which raises its per-transfer rate. That is why FertilityList ranks on live births per intended retrieval. See how to read IVF success rates.
• Ask about policy, not just numbers. Ask whether the clinic freezes all embryos by default, whether a fresh transfer is offered, and what drives the choice.
• Ask about costs. Freezing, storage and frozen-transfer cycles are often billed separately.
• Ask about storage safety. With most transfers now frozen, the lab’s freezing and storage systems matter to almost every patient. See SART membership and lab accreditation.

Questions to ask a clinic

1. What share of your transfers are frozen, and why?
2. Is a fresh transfer an option for me? What would make you recommend one or the other?
3. What are your live-birth rates per intended retrieval for my age group?
4. What do freezing, annual storage and each frozen-transfer cycle cost?

The CDC cautions that clinic comparisons may not be meaningful because patient populations differ.^[4] Use these figures to frame questions, not to draw conclusions about any one clinic.

Compare clinics by state. This guide is general information, not medical advice.