Embryo transfer: what happens and when to test
An embryo transfer is the step of IVF in which an embryo created in the laboratory is placed in the womb, usually a few days after the eggs were collected and fertilized. This guide explains what happens, how many embryos are used, what the evidence says about the days after, and when the pregnancy test is usually done.
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Medically reviewed by Dr Mary Davidson, Reproductive endocrinologist, checked on
Seek help now if you have any of these symptoms
Bleeding and cramping are common in early pregnancy and often do not mean miscarriage. The symptoms below, however, need to be assessed straight away.
- Soaking two or more sanitary pads per hour, or passing large clots
- Severe lower abdominal pain, especially on one side
- Pain at the tip of the shoulder
- Dizziness, fainting, or collapse
- Signs of shock — pale, clammy, rapid heartbeat, breathlessness
- Pain on opening bowels, or bladder or bowel changes
- Feeling very unwell, or feverish
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Problems can still arise after a transfer, and the HFEA lists ectopic pregnancy among the risks of IVF (HFEA, "In vitro fertilisation (IVF)", 2026). The NHS treats bleeding in pregnancy as an emergency when it comes with severe abdominal pain, pain in the shoulder, or feeling sick, faint or dizzy, and when it is heavy enough to soak a period pad soon after you put it on (NHS, "Vaginal bleeding in pregnancy", 2026). In the UK, call the emergency number or go to A&E, the hospital emergency department; in the US, call the emergency number or go to the nearest emergency room. The box above shows the emergency and urgent numbers for where you are, and get help now lists the other symptoms that need checking straight away. Your fertility clinic will also have its own number for problems during treatment.
What is an embryo transfer?
What is embryo transfer in plain terms? In IVF, eggs are collected and mixed with sperm in a laboratory. If fertilization succeeds, the HFEA says the embryos are allowed to develop for two to six days, which helps the embryologist select the strongest, and an embryo is then transferred to the womb in the hope that it continues to a successful birth (HFEA, "In vitro fertilisation (IVF)", 2026). The IVF embryo transfer is that last step of a treatment cycle; the HFEA lists the stages as suppressing natural hormones, boosting the egg supply, egg collection, mixing eggs and sperm, and finally embryo transfer.
The embryo transfer process
The embryo transfer process is short and usually needs no anesthetic. The sources describe it this way:
- Timing. The HFEA says the embryo is transferred two to five days after fertilization, and that no anesthetic is needed unless a condition would make the procedure painful (HFEA, "In vitro fertilisation (IVF)", 2026).
- The procedure. The NHS describes the embryo being put in the womb through a thin tube inserted through the vagina (NHS, "IVF", 2025). The Gateshead fertility unit, part of the NHS in the north of England, tells its patients the procedure is similar to a smear test: a fine catheter carrying the embryo is passed through the cervix while the abdomen is scanned so the embryo is placed accurately (Gateshead Health NHS Foundation Trust, "IVF booklet", 2024).
- Ultrasound guidance. The American Society for Reproductive Medicine reviewed each step of the transfer in a 2017 guideline. It found good evidence, from 10 randomized trials, for using abdominal ultrasound guidance during the transfer to improve clinical pregnancy and live-birth rates (ASRM, "Performing the embryo transfer: a guideline", 2017).
- Medication afterward. The HFEA says medication is used to prepare the lining of the womb, usually as a pessary or gel (HFEA, "In vitro fertilisation (IVF)", 2026). The Gateshead booklet says its patients take progesterone from the egg collection until the pregnancy test, to keep the lining receptive (Gateshead Health NHS Foundation Trust, 2024). Your clinic prescribes and explains this.
- The test date. You are given a date to do a pregnancy test, set out below.
Mock embryo transfer
Some clinics do a practice run first. The Gateshead booklet describes a catheter test, sometimes called a mock embryo transfer, used if you have had treatment to the cervix or a difficult transfer before: a fine soft catheter is passed through the cervix, much as in the real transfer, to find the route to the womb and make the transfer itself easier (Gateshead Health NHS Foundation Trust, 2024). The ASRM guideline reports one trial in which ultrasound guidance added nothing when a mock transfer had already been found easy (ASRM, 2017).
Day 3 and day 5 transfers
Embryos are transferred at different stages. The HFEA describes embryos at the two to eight cell stage and, later in their development, at the blastocyst stage (HFEA, "Embryo freezing", 2026). The Gateshead unit's policy speaks of day-5 transfers of blastocysts (Gateshead Health NHS Foundation Trust, 2024), which is why a 5 day embryo transfer is also called a blastocyst transfer. The Gateshead unit says most of its transfers take place 5 days after egg collection, and occasionally 3 days after, if only one embryo has developed, with the decision made by the embryology team (Gateshead Health NHS Foundation Trust, 2024). So how many days after egg retrieval is embryo transfer? Usually 3 or 5, within the HFEA's range of 2 to 5 days after fertilization, and your clinic decides which.
The day matters for dating the pregnancy. ACOG says the due date after IVF is set from the age of the embryo and the date of transfer: 261 days after a day-5 transfer and 263 days after a day-3 transfer (ACOG Committee Opinion 700, 2017). The IVF due date calculator applies those counts.
How many embryos are transferred
Usually one. The HFEA says that when several good-quality embryos are created it is normally best practice to freeze the rest, because putting two embryos back increases the chance of twins or triplets, which carries health risks (HFEA, "In vitro fertilisation (IVF)", 2026); it lists multiple pregnancy as the main risk and says usually one embryo is transferred (HFEA, "Embryo freezing", 2026). The NHS says that if you have more than one embryo, the doctor will discuss the risks and benefits of putting in more than one (NHS, 2025).
How a clinic decides can be seen in the Gateshead unit's published policy. It sets a mandatory single embryo transfer on day 5 for patients with a good outlook in their first or second cycle, and allows a discussion of two embryos in some situations with a poorer outlook or where fewer good-quality embryos are available, as the patient's choice (Gateshead Health NHS Foundation Trust, 2024). That is one unit's policy, shown as an example; your own clinic's policy is the one that applies.
Fresh and frozen embryo transfer
A fresh embryo transfer uses an embryo from the same cycle in which the eggs were collected. A frozen transfer uses one stored from an earlier cycle, and the NHS says suitable leftover embryos may be frozen for future attempts (NHS, 2025). The HFEA says frozen embryos are just as safe as fresh ones (HFEA, "Embryo freezing", 2026). Fresh vs frozen embryo transfer differs mainly in how the womb is prepared and in the timeline, which the guide to frozen embryo transfer sets out step by step.
When to test after an embryo transfer
How long after embryo transfer can you test? The answer is the date your clinic gives you. The sources agree on that and differ only in the day:
| Source | What it says |
|---|---|
| NHS | You are given a pregnancy test and a date to use it, around 16 days after the embryo transfer; take the test on the date given to get an accurate result |
| Gateshead NHS fertility unit | A blood test at the unit 12 days after a day-5 transfer, or 14 days after a day-3 transfer |
| HFEA | You are given a date; try not to test early, as you may get a false result |
The NHS describes the date and the 16 days (NHS, "IVF", 2025), the Gateshead booklet its own blood test days (Gateshead Health NHS Foundation Trust, 2024), and the HFEA the advice against testing early (HFEA, "In vitro fertilisation (IVF)", 2026). US clinics set their own test day, and no national US figure was available to us for this page. Asking when to do a pregnancy test after a blastocyst transfer, or how many days post transfer you can test, has the same answer: your clinic's date.
The pregnancy test calculator on this site counts from ovulation in a natural cycle, so it does not apply to a pregnancy test after IVF; after a transfer, the clinic's date replaces it.
Blood test: beta hCG after embryo transfer
Many clinics use a blood test that measures hCG, the pregnancy hormone, rather than a home urine test; the Gateshead booklet says a blood test gives an accurate reading of how much pregnancy hormone there is (Gateshead Health NHS Foundation Trust, 2024). The clinic reads the result, sometimes alongside a repeat test a couple of days later or a scan. Why published ranges are too wide for one result to be placed on them is explained in the guide to hcg levels. If the test is positive, the NHS says you will be asked back for a scan at around 7 weeks of pregnancy to check the heartbeat and confirm the pregnancy (NHS, 2025).
What the evidence says about the days after
Searches for what to do after embryo transfer to increase success turn up long lists of tips. The ASRM guideline looked at the two that have been studied most:
- Bed rest. Of 14 studies in its review, none showed a benefit from bed rest of any length after a transfer. One randomized trial of 240 people in their first IVF cycle found a live-birth rate of 56.7% with walking straight away against 41.6% after 10 minutes of bed rest, which the guideline calls a noteworthy suggestion of harm. It concludes there is good evidence not to recommend bed rest (ASRM, 2017).
- Acupuncture. Trials have contradictory results, and the guideline concludes there is fair evidence that acupuncture around the time of transfer does not improve live-birth rates (ASRM, 2017).
The HFEA adds that there is no conclusive evidence that stress affects the outcome of fertility treatment (HFEA, "In vitro fertilisation (IVF)", 2026). The Gateshead booklet asks its patients to take things easy and avoid strenuous activity and sex for 1 to 2 weeks after the transfer (Gateshead Health NHS Foundation Trust, 2024). Your clinic's own instructions are the ones to follow.
People often look for signs in the days after a transfer. This page does not read them: the test on the clinic's date is what gives the result, which is why the HFEA asks you not to test early.
Embryo transfer success rates
How successful a transfer is depends on age and on the cause of infertility, the HFEA says, and it publishes the latest national figures on its research and data pages (HFEA, "In vitro fertilisation (IVF)", 2026). This page prints no rate, because a single figure says little about any one person's chances; the HFEA advises talking to your doctor about your own.
Your due date after a transfer
Because the age of the embryo and the transfer date are known, an IVF due date is more precise than one counted from a last period. The IVF due date calculator gives the embryo transfer due date from those two facts, and the same calculation applies after a frozen transfer. To see how far along you are at any point, the pregnancy week calculator gives the gestational age in weeks and days.
That count starts before the transfer. Clinics date an IVF pregnancy the same way as any other, as if from a last period two weeks before conception, so on the day of a day-5 transfer the pregnancy is counted as 2 weeks and 5 days along, and on the day of a day-3 transfer 2 weeks and 3 days. Two weeks after the transfer, it is 4 weeks and 5 days, or 4 weeks and 3 days. These figures are our arithmetic from ACOG's day counts, not numbers ACOG states (ACOG Committee Opinion 700, 2017).
This guide is information, not a diagnosis or a recommendation of treatment, and it is no substitute for your own clinician. See the medical disclaimer.
Sources
- Human Fertilisation and Embryology Authority. In vitro fertilisation (IVF). HFEA, 2026.
- Human Fertilisation and Embryology Authority. Embryo freezing. HFEA, 2026.
- NHS. IVF. nhs.uk, 2025.
- Gateshead Health NHS Foundation Trust. IVF booklet. gatesheadhealth.nhs.uk, 2024.
- Practice Committee of the American Society for Reproductive Medicine. Performing the embryo transfer: a guideline. Fertility and Sterility 107(4): 882-896, 2017.
- American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine and Society for Maternal-Fetal Medicine. Committee Opinion No. 700: Methods for Estimating the Due Date. ACOG, 2017.
- NHS. Vaginal bleeding in pregnancy. nhs.uk, 2026.
Frequently asked questions
How long after an embryo transfer can you test?
On the date your clinic gives you. The NHS says the test date is around 16 days after the transfer, and one NHS unit does a blood test 12 days after a day-5 transfer and 14 days after a day-3 transfer. The HFEA advises against testing early because the result may be false.
How many days after egg retrieval is the embryo transfer?
Usually 2 to 5 days after fertilization, which happens on the day of egg collection (HFEA). One NHS unit says most of its transfers are 5 days after egg collection, and occasionally 3 days.
Does bed rest after an embryo transfer help?
No. The ASRM guideline found that none of 14 studies showed a benefit from bed rest of any length, and recommends against it. One trial it describes found higher live-birth rates with walking straight away than with 10 minutes' rest.
2 weeks after embryo transfer, how many weeks pregnant am I?
Counted the way clinics date a pregnancy, about 4 weeks and 5 days after a day-5 transfer, and 4 weeks and 3 days after a day-3 transfer. On the transfer day itself a pregnancy is counted as 2 weeks 5 days or 2 weeks 3 days along. This is our arithmetic from the counts in ACOG Committee Opinion 700; the IVF due date calculator does it for you.