Fetal diagnostics in Norway

Fetal diagnostics is used to obtain information about the health status or genetic characteristics of the fetus, and is a service which is offered to pregnant women who are at greater risk of having a fetus with a severe hereditary disease or developmental abnormality.

Foto: Colourbox

​Some of the procedures, such as CUB tests (Combined Ultrasound and Biochemical, often called a double test) and NIPT/NIPD, are risk-free for the mother and the fetus. Samples from the placenta or amniotic fluid involve a procedure which results in a slight increase in the risk of miscarriage.

Who can be offered fetal diagnostics?

In Norway, pregnant women may be offered fetal diagnostics if:

  • They will be 38 years or older on the due date
  • The mother or her partner has previously had a child or fetus with a severe disorder or developmental abnormality
  • The mother or her partner are at greater risk of having a child with a serious condition which can be detected (examples are some hereditary diseases)
  • The mother is taking medications which can cause developmental abnormalities in the fetus
  • An ultrasound examination has detected signs of developmental abnormalities in the fetus
  • In special cases, if the woman/couple is in a difficult life situation and would not be able to cope with the additional burden that having a sick or disabled child can entail.

The use of fetal diagnostics is regulated by the Biotechnology Act and is voluntary. If you are offered fetal diagnostics, you should also be given comprehensive information and guidance regarding the examinations involved and the answers that they can provide.

Ultrasound examinations performed as part of ordinary prenatal care are not considered fetal diagnostics.

Information and genetic guidance

In connection with all fetal diagnostics, the mother and her partner should be given information about the examination before it is performed, among other things

  • that the examination is voluntary
  • whether there are risks associated with the examination
  • what the examination can reveal
  • the potential consequences of the results for the child, the mother and the family as a whole.

Genetic guidance in the event of a risk of a severe hereditary disease

The mother/couple will also be entitled to genetic guidance if there is an increased risk of the fetus having a severe hereditary disease. The mother/couple will often have undergone tests to determine the possibility of the fetus having a serious hereditary disease before the pregnancy, and will have been given genetic guidance in connection with this.

When a couple receives genetic guidance, qualified healthcare professionals will help the pregnant woman/couple to understand:

  • the medical information
  • the risk of having a child with the disease
  • how the disease may progress
  • the treatment options that are available

Information once the results of the examinations become available

If a fetal diagnostic examination shows that the unborn child may have a disease or developmental abnormality, the woman/couple should be given genetic guidance and information concerning:

  • the disease or condition concerned
  • applicable rights and appropriate relief measures

Ultrasound examination during week 11–14 and blood sample from the mother (CUB test)

A CUB test (double test) is a combination of a fetal diagnostic ultrasound examination during week 11–14, often known as an "early ultrasound", and the taking of a blood sample from the mother. The CUB test does not lead to a diagnosis, but enables the likelihood of the fetus having certain specific chromosomal abnormalities to be determined.

Between weeks 11 and 14 during a pregnancy, all fetuses have a slight swelling under the skin of the neck (nuchal translucency/nuchal fold). An ultrasound examination involving the measurement of nuchal translucency is performed between week 11 and 14 of pregnancy.

If the swelling of the neck is larger than normal, there is a greater probability of chromosomal abnormalities in the fetus. Trisomy is an example of a chromosomal abnormality, where the fetus has an extra copy of chromosome 13, 18 or 21, also known as

The most common of these is trisomy 21 - Down's syndrome.

The probability of trisomy 13, 18 and 21 is calculated by combining the measurement of neck translucency with the results of blood samples taken from the mother (double test), other information about the mother and other information obtained during the ultrasound examination.

Increased swelling of the neck can also be observed in other conditions, such as heart defects. The fetus may be completely healthy even if the examination shows an increase in swelling under the skin of the neck.

What happens in practice?

In order to have a fetal diagnostic ultrasound examination, you must be referred by your doctor, your midwife or a department of fetal medicine or medical genetics. The referral must state the date of the last menstruation and the reason why you are being referred.

If you are offered a CUB test, you will be given more information by the department of fetal diagnostics/medical genetics concerning the procedure and when you will have a blood sample taken.

You will be summoned to an ultrasound examination during pregnancy week 11–14, as determined from the date of your last menstruation or information from previous ultrasound examinations.

The procedure is usually performed as an ultrasound examination of the abdomen (abdominal), but an ultrasound examination via the vagina (vaginal) provides a clearer overview. The procedure does not normally hurt and it is not dangerous for the fetus.

How long does it take to get the results?

You will normally be told the results of a CUB test immediately after the ultrasound examination. If the results of the blood test are not ready by the time of the ultrasound examination, you will receive the final results of the CUB test by telephone or letter. This can take up to two weeks.

The CUB test will not lead to a confirmed diagnosis, as it only calculates the probability that a condition exists. Only a placenta or amniotic fluid test can provide a confirmed diagnosis. If the examination shows that the probability is above a specific threshold (1:250), your doctor will discuss with you your options regarding NIPT, placenta and amniotic fluid tests.

NIPT for trisomy

A NIPT (Non-Invasive Prenatal Test) is an analysis of the fetus's DNA (genetic material) which is present in the blood of the pregnant woman. By analysing the blood sample from the mother, it is possible to obtain information about the genetic characteristics of the fetus.

The analysis is used to determine whether a fetus has certain hereditary diseases or chromosomal abnormalities, and can be used to investigate whether the fetus may have:

NIPT is most precise for detecting or eliminating the presence of trisomy 21. The test is a little less precise for trisomy 13 and 18. These conditions are much less frequent than trisomy 21.

Who will be offered NIPT for trisomy?

In Norway, NIPT is not routinely offered to all pregnant women. The test will only be offered if the CUB test has indicated an increased probability that the fetus has trisomy 13, 18 or 21. This probability must be greater than 1:250.

The test is risk-free for both you and the fetus, and is therefore offered as an alternative to a placenta test or amniotic fluid test. If the probability of trisomy is very high, it may nevertheless be appropriate to take a placenta or amniotic fluid sample without taking an NIPT sample.

The placenta and amniotic fluid samples can show whether the fetus could have chromosomal abnormalities other than was indicated by the NIPT. You will be given guidance on this where appropriate.

Women who are pregnant with multiple fetuses cannot usually have a NIPT.

What happens in practice?

A blood sample will be taken from you at a hospital approved by the Norwegian Directorate of Health. In some cases, approved hospitals have agreements with GPs who can who take blood samples on their behalf. You will be notified of this when appropriate. The sample will be sent to a laboratory, which will perform the analysis.

Only doctors at hospitals approved by the Directorate of Health can order this analysis. The university hospitals of Tromsø, Trondheim, Bergen, Stavanger and Oslo are approved for this.

Other Norwegian doctors should not take blood samples for NIPT or send blood samples abroad for analysis.

How long does it take to get the results?

The results of the analysis can be expected within 10–14 days. The doctor treating you will contact you in the way you agreed, in order to inform you of the results.

Are there any risks associated with the procedure?

There are no risks associated with the procedure itself. The doctor treating you will explain how certain the results of the NIPT are and whether it will be necessary to carry out more tests at a later date. If an NIPT shows a high probability that the fetus has a trisomy, it is recommended that a placenta sample or amniotic fluid sample be taken in order to make a confirmed diagnosis.

NIPT or NIPD for other conditions

NIPT for gender determination

NIPT may also be offered when the pregnant woman/couple are at greater risk of having a child with a severe hereditary disease which is linked to the sex of the child, that is a hereditary disease that mainly affects boys.

An NIPT will then be performed in order to determine the gender of the fetus. The test determines the gender very accurately, but it cannot show whether or not the unborn child will have the disease. If the fetus is male, the woman will therefore be offered a placenta test or amniotic fluid test to determine whether the fetus has inherited the genetic defect concerned.

Placenta tests and amniotic fluid tests give a definite result. If the fetus is female, no further fetal diagnostic procedures will be necessary.

NIPD for diseases related to specific genes

NIPD (Non-Invasive Diagnostics) may be appropriate if the pregnant woman/couple are at greater risk of having a child with a severe hereditary disease associated with a specific gene. Most cases involve genetic defects which can lead to serious diseases and which have been demonstrated in the pregnant woman or the father of the child (dominant inheritance) or in both (recessive inheritance).

NIPD has been developed for certain severe hereditary diseases associated with a single gene. Medical genetics departments will know whether it is possible to offer NIPD instead of a placenta test or amniotic fluid test for different diseases.

Placenta test

The placenta develops from the fertilised egg and therefore reflects the DNA (genetic material) of the fetus. A placenta test is an analysis of cells from the placenta. The test can provide a definite result as to whether or not the fetus has a trisomy, such as Down's syndrome. The placenta test can also give an answer as to whether or not the fetus has inherited a genetic defect which has led to a serious illness in the family.

Who will be offered a placenta test?

Pregnant women who have shown a high probability of having a child with trisomy or a specific serious hereditary disease or condition will be offered a placenta test.

In order to have a placenta test carried out, the woman must be referred by her doctor/midwife to a department of fetal medicine or a department of genetic medicine. The referral must state the date of the last menstruation and the reason why the woman is being referred.

What happens in practice?

The procedure will be carried out from week 10 of the pregnancy, usually during week 11–14.

Placenta tests can be performed in one of two ways:

  • through the abdomen (transabdominal)
  • via the vagina through the cervix (transcervical)

An exploratory procedure will first be performed to determine the size of the fetus and the method that will be most appropriate. The method used will depend on the location of the placenta.

Under ultrasound guidance, a needle is inserted through the abdomen into the placenta, and a little sample of tissue is then drawn out of it. Alternatively, an instrument with a small catheter or clamp can be inserted into the placenta under ultrasonic guidance, and a small sample of tissue taken.

The procedure may hurt a little. Different people experience the pain in different ways; for most people, it is about the same as when a cell specimen is taken from the cervix.

You must wait about 15 minutes before leaving the hospital after the test. You may be advised to take it a bit easier than normal for two to three days after the procedure. It will normally not be necessary to take sick-leave.

How long does it take to get the results?

The time it takes to get the results will depend on what is being tested. You will be informed of the waiting time when you are given genetic guidance or when the sample is taken. You will receive a letter or telephone call when the test results are available.

Are there any risks associated with the procedure?

Approximately 0.5 percent of those who undergo a placenta test may suffer a miscarriage as a result of the sampling procedure. Any miscarriage will usually occur during the first week after the sampling procedure.

Amniotic fluid test

Amniotic fluid contains cells from the fetus which can be analysed by a genetic laboratory. An amniotic fluid test is an analysis of cells taken from the amniotic fluid. The test can provide a definite result as to whether or not the fetus has a trisomy, such as Down's syndrome.

An amniotic fluid test can also indicate whether or not the fetus has inherited a genetic defect which has led to a serious illness in the family. An amniotic fluid sample will normally be taken later in the pregnancy than a placenta sample, from week 15 and 0 days.

Who will be offered an amniotic fluid test?

Pregnant women who have shown a high probability of having a child with trisomy or a serious hereditary disease may be offered an amniotic fluid test. In order to have an amniotic fluid test performed, the woman must be referred by her doctor/midwife to a department of fetal medicine or genetic medicine. The referral must state the date of the last menstruation and the reason why the woman is being referred.

What happens in practice?

Before the amniotic fluid sample is taken, an ultrasound examination will be performed to determine the size of the fetus, the location of the placenta and the point where the needle should be inserted.

An amniotic fluid sample is taken by inserting a thin needle under ultrasonic guidance into the amniotic cavity and extracting approximately 15 ml of amniotic fluid. This procedure may hurt a little, much like a normal blood test.

You will have to wait about 15 minutes before leaving the hospital. You may be advised to take it a bit easier than normal for two to three days after the procedure. It will normally not be necessary to take sick-leave.

How long does it take to get the results?

The time it takes to get the results will depend on what is being tested. You will be informed of the waiting time when you are given genetic guidance or undergo the sampling procedure. You will receive a telephone call or letter when the test results are available.

Are there any risks associated with the amniotic fluid test?

Approximately 0.5 percent of women who undergo an amniotic fluid test may suffer a miscarriage as a result of the sampling procedure. Any miscarriage will usually occur during the first week after the sampling procedure.