Beta-hCG after a transfer: how to interpret the figure, and the next one

On the day of the blood test, many patients send me a photo of the result before they’ve even understood what it means. This is normal: after weeks of waiting, a single figure is difficult to interpret. Here are some useful pointers, with one caveat from the outset: interpretation is always the responsibility of your doctor, who is familiar with your treatment plan.

What beta-hCG measures

Human chorionic gonadotrophin (hCG) is produced by the cells of the developing placenta as soon as the embryo implants. Its blood level rises rapidly at the start of pregnancy. A blood test is more accurate than a urine test: it provides a numerical value, in IU/L (or mIU/mL, which is the same thing).

When to have the blood test

Generally 9 to 11 days after a blastocyst transfer (day 5), or 12 to 14 days after a day-3 transfer. If carried out too early, the result may be negative even though implantation is underway, or positive due to the trigger injection if it contained hCG: this residue usually disappears within 10 to 14 days.

Thresholds, for guidance only

• Less than 5 IU/L: test considered negative.
• Between 5 and 25–50 IU/L: uncertain range. Implantation has taken place, but the level is low for the day; a second test is essential.
• Above approximately 50 to 100 IU/L 10–11 days after a blastocyst transfer: an encouraging result. The higher the first figure, the greater the likelihood of a developing pregnancy, although no single threshold guarantees anything.

These reference points vary depending on the laboratory and the exact day of the test. A level of 80 at day 9 and a level of 80 at day 12 do not tell the same story.

The second test: the real test

At the start of a developing pregnancy, beta-hCG doubles approximately every 48 to 72 hours. A blood test is therefore repeated two days later. Most doctors consider that an increase of at least 50 to 60 per cent within 48 hours is consistent with a pregnancy progressing normally. A slower rise, a plateau or a fall suggest a biochemical pregnancy or, more rarely, an ectopic pregnancy.

With twins, levels are often higher, but it is not possible to count the embryos from a blood test: only an ultrasound scan can confirm this.

A cause for concern: a level that is rising too slowly

Following IVF, the risk of ectopic pregnancy is around 1–2 per cent, slightly higher than with natural conception, particularly if the fallopian tubes are affected. A beta-hCG level that rises slowly or remains stable, combined with pain on one side of the abdomen, bleeding or feeling unwell, requires prompt medical attention. This is not the most common scenario, but it is one that must not be missed.

Following a positive result

• Do not stop treatment (progesterone, sometimes oestrogen) without explicit instructions. It is generally continued until 8 to 12 weeks of pregnancy.
• Ultrasound scan at around 5 to 6 weeks of pregnancy to see the gestational sac in the uterus, then at around 7 weeks to check for a heartbeat.
• Send the results to the IVF clinic: they need them for follow-up and statistical purposes.

If you have returned home, the blood test can be carried out at any laboratory; simply send the result to the clinic. I explain how the handover works in the article on pregnancy monitoring after returning home.

After a negative result

Your doctor will tell you when to stop treatment; your period usually starts a few days later. A failed transfer of a good-quality embryo is common and does not necessarily mean there is a problem. It is time to take stock, without rushing, of what comes next — and to look after yourself.

Frequently asked questions