Moving frozen embryos and eggs across borders: what it actually involves

Almost nobody starts treatment thinking about shipping. Then a cycle ends, and there are four blastocysts in a tank two thousand kilometres from where you now live — or where you now want to continue.

This is not an unusual situation. Preliminary 2023 data from the European IVF Monitoring Consortium, presented at ESHRE in July, recorded 401,483 frozen embryo transfer cycles against 158,649 conventional fresh cycles. Freezing is no longer the exception; it is the default pathway. Which means a growing number of patients have material in storage, and sooner or later some of them need to move it.

What actually gets moved, and how

Frozen embryos, eggs and sperm are held in liquid nitrogen at around −196 °C. They cannot be allowed to warm at any point, so they do not travel in an ordinary cooler or in your luggage.

They travel in a dry shipper: a vacuum-insulated vessel with an absorbent lining charged with liquid nitrogen, which holds cryogenic temperature using nitrogen vapour rather than a free liquid. Because there is no sloshing liquid, it can be handled and transported. Specialist couriers add continuous temperature logging and, increasingly, GPS tracking, so the shipment can be audited afterwards.

The single question that matters most about the container is its hold time — how many days it stays at temperature once charged. Ask the courier for the validated hold time of the specific unit being used, and compare it against the realistic worst case for your route, including customs delays. A shipment that arrives inside its hold time is fine. One that does not is not recoverable.

The paperwork chain

Transport is rarely blocked by the physics. It is blocked by documentation. Clinics generally will not release material without a complete chain, and the pieces usually include:

• A written release authorisation from you, naming what is being released and to whom. Where material was created with a partner or a donor, both parties’ consents may be required — and consent forms signed years earlier may not cover transport at all.
• An acceptance letter from the receiving clinic, confirming it agrees to take custody and has storage available.
• Courier authorisation, giving a named company permission to collect.
• Current infectious-disease screening for the people whose gametes are involved — typically HIV, hepatitis B and C, and syphilis. Many receiving labs require results within a defined recency window, so old results may need repeating.

Requirements vary by country and by clinic, and no two labs word this identically. Get the receiving clinic’s checklist in writing first, then take it to the storing clinic — not the other way around. Chasing a document the sending lab never mentioned is the most common source of delay.

Questions to settle before anything is packed

Who holds responsibility at each stage? Ask, in writing, where custody passes from the sending lab to the courier and from the courier to the receiving lab. Ask what the courier’s liability actually covers if a shipment fails — in most cases it is the cost of transport, not the value of what was lost, which is not the same thing at all.

What does the quote include? A serious quote itemises collection, the container, transport, customs handling and delivery. Ask separately what the receiving clinic charges to accept and store the material, and for how long that is covered.

Has the receiving clinic done this before, from your country? A clinic in Mexico that regularly receives international shipments will name the couriers it works with and describe its intake procedure without hesitating. One that has not will improvise, and you do not want to be the case they learn on.

What is the plan if the shipment is delayed? Customs holds happen. Ask what the courier does if a shipment is stopped, and who is authorised to act on your behalf.

Are you moving everything, or splitting it? Some patients deliberately leave part of a cohort in the original lab rather than putting every embryo on one aeroplane. It costs more in storage. It is also the only real hedge against a single catastrophic failure.

The unglamorous conclusion

Cross-border transport is routine, and it works — but it works because a lot of specific, boring things were checked in advance by people who had done it before. Nothing here is medically complicated. It is logistics, and logistics reward the patient who asks for the checklist early.

If you are weighing where to continue treatment rather than how to move what you already have, the patient journey walks through how a plan gets built from the beginning.