When the pregnancy test is positive, but the pregnancy does not progress normally.
What is it really?
In case of IVF treatment, the pregnancy test (levels of β-HCG in blood) is scheduled exactly 14 days following the egg collection. If the test is positive, then the woman is pregnant.
Human Chorionic Gonadotrophin (β-HCG) is a hormone produced by the placenta following implantation of the embryo in the uterus. It can be detected and measured in blood, as well as in urine. The blood test is generally considered more reliable.
Normally, β-HCG levels double every 2 days. This is why the doctor will ask you to repeat the test 2-3 times. If β-HCG levels double every 2 days, then that is a very good sign that the pregnancy progresses normally. A 60% increase is sufficient. However, in some cases, β-HCG levels
- Either do not increase as expected and start to decline until they become zero
- Or remain stable and then gradually decline.
This is a ‘biochemical pregnancy’, meaning a pregnancy that was diagnosed only by the β-HCG levels, but it cannot be detected by ultrasound scan.
Does it happen only after IVF?
The answer is ‘No’. It also happens following natural conception. If your period is delayed for 3-4 days, it is possible that it has happened to you, too. Biochemical pregnancies are not uncommon. Women undergoing IVF have their cycle monitored very closely, have blood tests done often and that’s why they can find out that they had a biochemical pregnancy. If they didn’t have the β-HCG test on that exact day, they might have never found out that they had a biochemical pregnancy.
Obviously, a biochemical pregnancy can cause great disappointment, even frustration. The pregnancy test was positive, but now there is no pregnancy…
Why does it happen?
A biochemical pregnancy is in fact a miscarriage that just happened too soon. Usually, it occurs because of a pathological embryo, i.e. an embryo with chromosomal abnormalities. If an embryo has the wrong number of chromosomes, then it cannot survive. Chromosomal abnormalities are generally rare, but tend to be more common in older women and in women with polycystic ovaries.
Other causes of a biochemical pregnancy:
- ‘Hostile’ endometrium or endometrium with abormalities, such as uterine septum, fibroids or polyps.
- Thyroid dysfunctions.
All women trying for a baby naturally or with IVF should have their uterus and thyroid gland checked.
Will it affect a future pregnancy?
Just because it happened once, doesn’t mean it will happen again. A biochemical pregnancy is not considered to be a negative factor for a future IVF success. On the contrary, it is preferred compared to a negative result because it proves that the first stages of the pregnancy did actually take place. In the other hand, it causes sorrow and disappointment…
Our advice to couples is to leave this negative experience behind as quickly as possible and move forward. It is important to have a consultation with your fertility expert. The doctor may ask you to do some more tests to determine the causes of the biochemical pregnancy. When you try IVF the next time, the goal is not only a positive pregnancy test, but also the pregnancy to progress normally.
The real problem is when a woman has more than 1 biochemical pregnancies either following natural conception or IVF. In that case, thorough investigations are needed in order to pinpoint the cause and to decide how to solve the problem.