The waiting period between artificial insemination or IVF and finally being able to take the deciding pregnancy test is something that every woman undergoing fertility treatment has to experience.

This exciting but at times also quite anxious time is commonly known as the two-week wait (2ww) and is also the topic of today’s article.

Why is it called the two-week wait?

The two-week wait gets its name from the time frame it takes the uterine wall to release enough hCG hormone to be detected in a blood pregnancy test. This usually takes about, who guessed it, 14 days.

But what is the hCG hormone and what does it do?

HCG (human chorionic gonadotropin) is a hormone released by the embryo’s trophoblastic cells after it has implanted in the womb. This hormone is in charge of promoting the release of progesterone which, in turn, enables the development of the uterine lining and the growth of the embryo.

During foetal development, the hCG hormone level gradually increases until it begins to slowly decrease starting in the 2nd or 3rd month of pregnancy.

Why is the 2 week-wait necessary?

For the blood test to be able to detect a pregnancy, the hCG hormone is measured. As already mentioned above, the hCG hormone level is an indicator that the implantation of an embryo has occurred. But if this blood pregnancy test is performed too early on, the hCG levels might be too low for the test to be able to detect them.

Therefore, it is recommended to wait at least 10-14 days before performing the blood pregnancy test in order to avoid false-negative results. Even though a urine test is another possible way of determining the beta-hCG level, fertility specialists always recommend performing a blood test to determine pregnancy since urine tests are limited to inferior levels of mUI/ml (international miliunits per millilitre) and are more likely to result in a false negative.

False negatives and false positives

In the last paragraph, we mentioned “false-negative” results when doing a pregnancy test after the 2 week-wait. But why can this happen?

We speak of false-negative results when the pregnancy test turns out to be negative even though the patient is pregnant. This can occur when the test has been performed too early on when the beta-hCG hormone level is still below the detectable limit.

In the same way a false-negative can happen, a false-positive result is not impossible either. There are a few reasons which could explain a false-positive, even this situation is not very common. The most frequent ones are due to biochemical pregnancies; also an ectopic pregnancy can explain the false-negative or even recent miscarriages in which the hCG level has not adjusted yet. It could also happen due to the injection of some medication (that have hCG as an active ingredient), between other reasons.

To avoid either false result, the blood-pregnancy test should be taken after the 2 week-wait and not too close to insemination or transfer, when traces of medication may still be present in the bloodstream.

How should I behave during the 2 week-wait?

It is important to stay calm and relaxed. Don’t go crazy imagining what the results will be. You will find out soon enough and no matter how much you think about it, you won’t be able to influence the result anyways.
If you experience bleeding between the first and second week of pregnancy, don’t fall into a state of panic. This is more common than you think - 1 in 3 women experience so called implantation bleeding. This may even be the first obvious sign that the embryo has implanted.

Stress is never good for your body, therefore, try to take your mind off of the treatment for a while and focus on things that you enjoy and that make you happy. Spend time with your loved ones or pick up an old hobby that can keep you busy and relaxed.

We know it’s easier said than done and that’s exactly why at IVF-Spain it is very important to us to offer our patients good communication to make them feel, not only physically, but also emotionally prepared and supported for every step of their treatment.