Fetal diagnostics

Fetal diagnostics is used to obtain information about the health status or genetic characteristics of the fetus. It 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.

Ultralydundersøkelse på kvinne

Illustration: Colourbox

What is fetal diagnostics?

Fetal diagnostics consists of ultrasound examinations and tests on samples of placenta and amniotic fluid. It is also possible to obtain information about the characteristics of the fetus by performing non-invasive prenatal testing (NIPT) or non-invasive prenatal diagnosis (NIPD). Both tests analyse the DNA of the fetus in a blood sample from the mother.

New fetal diagnostics

All pregnant women will eventually be offered an ultrasound examination during the first trimester of their pregnancy through the national health service, but it will take time for this service to become available to everyone. The service will be made available during 2022.

All pregnant women aged 35 or over on their due date will be offered an ultrasound examination and NIPT during 2021. More information will be released once the service becomes available.

Until the new service is in place, the current regulations and rights regarding fetal diagnostics will continue to apply.

Proposal for organisation and introduction of NIPT and ultrasound examinations during the first trimester - Norwegian Directorate of Health (in Norwegian)

Who can be offered fetal diagnostics?

Until the new service is introduced, you will be entitled to have fetal diagnostics performed via the national health service if:

  • you will be 38 years of age or over on your due date
  • you or your partner have previously had a child or fetus with a serious medical condition or developmental abnormality
  • you or your partner are at greater risk of having a child with a serious medical condition which can be detected, e.g. hereditary diseases
  • you are taking medicines which can cause developmental abnormalities in the fetus
  • an ultrasound examination has revealed signs of developmental abnormalities in the fetus
  • you are facing a difficult life situation and do not believe you could cope with the strain of having a sick or disabled child

Being anxious that your pregnancy will not develop in the normal way does not entitle you to fetal diagnostics.

If you are entitled to fetal diagnostics and would like to have a fetal examination, you should contact your midwife or doctor early in your pregnancy. They will be able to provide you with information about fetal diagnostics and refer you for guidance and examinations in the national health service.

Once ultrasound examinations during the first trimester have been made available to all pregnant women, some of the rules for being offered fetal diagnostics will change.

Fetal diagnostics is voluntary

It is you, as the mother-to-be, who decides whether or not you wish to accept the offer of fetal diagnostics and who consents to the procedures.

You should ideally find out more about what fetal diagnostics entails before your first pregnancy check-up. This will make it easier for you to ask questions during your check-up.

Your midwife or doctor will provide you with appropriate, neutral information about fetal diagnostics during your first consultation, to enable you to make the decision that is right for you.
If you need an interpreter, you should state this when booking your appointment.

You may be faced with dilemmas

It might be a good idea to consider the possible dilemmas that you might have to face depending on the results of your fetal diagnostics. Although most fetuses are healthy, some pregnant women find that the examinations and tests provide unexpected information about their unborn child, e.g. that it has a medical condition or a major or minor developmental abnormality.

The results of your examinations may also be inconclusive, with the result that you will have to undergo further investigations in order to arrive at a conclusive answer.

Right to information and genetic counselling

Information about the examinations

You and your partner have the right to receive information about the procedures you will undergo before they are performed. You can then decide whether or not you wish to have the procedures based on the information you are given. The information you receive will depend on the examination concerned. You should be told about:

  • the risks associated with the procedure
  • what the procedure involves
  • what the procedure could reveal, how safe it is and how soon you will find out the results
  • the consequences that the results could have for your unborn child, for you and for your family as a whole
  • what will happen next if the procedure shows that your unborn child has a medical condition or developmental abnormality

Genetic counselling linked to the risk of serious hereditary diseases

You are entitled to genetic counselling if you know that there is a serious hereditary disease in either your family or your partner's family, and that you are therefore at greater risk of having a child with the same disease. You will then be referred to a university hospital with a department of medical genetics or a centre for fetal medicine in your health region.

You will be given guidance and counselling by a health professional with specialist expertise, normally a genetic counsellor or a specialist in medical genetics.

You will be informed in a clear and understandable way about:

  • medical facts about the condition that is being investigated
  • the type of fetal diagnostics that can provide information about the condition and how long it will take to find out the results
  • the likelihood of having a child with the condition
  • how the condition could develop in the future
  • the treatment options that are available

When will the results of the procedure be ready?

If the procedure shows that your unborn child has a medical condition or developmental abnormality, you will be given more information about:

  • the disease or condition concerned
  • whether more procedures will be necessary in order to confirm the diagnosis
  • your rights, follow-up and relevant support

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

A CUB test is a combination of a fetal diagnostic ultrasound examination during week 11–14, often known as an “early ultrasound”, and a blood sample taken from the mother. The blood sample is analysed to determine the levels of two hormones (double test).

The CUB test does not lead to a diagnosis, but enables the likelihood of the fetus having trisomy 13, 18 or 21 to be determined.

Trisomy is a chromosomal abnormality. The fetus will then have an extra copy of chromosome 13, 18 or 21. These are known as:

The most common of these is trisomy 21, also known as Down syndrome.

Ultrasound examination during week 11-14

During the ultrasound examination in the first trimester, your midwife or doctor will find out whether the fetus is alive, work out the duration of the pregnancy and assess the anatomy of the fetus (head, body, etc.).

The ultrasound examination will also show whether there are one or more fetuses, and whether or not any twins have a shared placenta. Twins with a shared placenta need special support.

The ultrasound examination can provide early information about a number of serious conditions and developmental abnormalities in the fetus. It can also provide information about the presence of any conditions which would mean that you and/or the fetus will need special support.

The ultrasound examination is normally performed on the stomach, but an examination performed via the vagina sometimes gives a clearer picture.

The procedure does not hurt and is harmless for the fetus. The entire procedure, including the provision of information by the midwife or doctor, takes between 20 and 45 minutes.

Measurement of nuchal translucency (nuchal fold)

An ultrasound examination involving measurement of nuchal translucency is performed between weeks 11 and 14 of pregnancy. During this period of the pregnancy, all fetuses have a slight swelling under the skin on the neck.

If the nuchal translucency is larger than expected, this could be a sign of an increased likelihood that the fetus has chromosomal abnormalities. Trisomy is an example of a chromosomal abnormality.

The risk or likelihood of trisomy 13, 18 and 21 is determined based on the nuchal translucency, along with information about you and the results of the hormone tests.

A large nuchal translucency can also be seen with other conditions, such as heart defects or certain genetic diseases. The fetus may be completely healthy even if the procedure indicates an increased nuchal translucency.

Who will be offered an early ultrasound and a CUB test?

If you will be 38 years of age or older on your due date or you are entitled to fetal diagnostics for any other reason, you will be offered an ultrasound examination during weeks 11-14, with measurement of the nuchal translucency (nuchal fold) and possibly a double test (CUB test). This may also be relevant for other pregnant women with indication for fetal diagnostics. 

What happens in practice?

The timing of the ultrasound and blood test will be determined during your first consultation with the midwife or doctor. It will be determined from the time of your last menstruation. If you are not sure when this was, it may be necessary to determine the duration of your pregnancy and whether the fetus is alive via a simple ultrasound examination.

You will then be referred by your midwife or doctor for a consultation at a department of medical genetics or a centre for fetal medicine. During your consultation, you be given guidance on the service and the procedure itself, and you can make an appointment for your ultrasound examination and any blood test.

If the ultrasound examination shows signs that the fetus has trisomy 13, 18 or 21 or a developmental abnormality, you will be offered further tests (such as a NIPT, a placenta or amniotic fluid test, or a more comprehensive ultrasound examination).

If there are any signs of trisomy, it may be appropriate to have a placenta or amniotic fluid test instead of a NIPT, because the results of these tests can provide a definitive diagnosis.

NIPT for trisomy 13, 18 and 21

A NIPT (non-invasive prenatal test) is an analysis of a blood sample which is taken from you in order to analyse genetic material (free DNA) from the placenta. The placenta and fetus usually have the same DNA characteristics. By analysing the free DNA from the placenta in your blood sample, you can obtain information about the genetic characteristics of the fetus.

A NIPT is used to investigate whether a fetus has specific hereditary diseases or chromosome changes. A NIPT is more precise than a CUB test, as it is able to detect or disprove the presence of trisomy 13, 18 or 21 with greater precision.

Trisomy is a chromosomal abnormality. The fetus will then have an extra copy of chromosome 13, 18 or 21. These are known as:

The most common of these is trisomy 21, also known as Down syndrome.

A NIPT is the most precise method for detecting trisomy 21. Trisomy 13 and 18 are both rarer than trisomy 21. The test is risk-free for both you and your unborn child.

Who will be offered a NIPT for trisomy?

If you will be 38 years of age or over on your due date or you are entitled to fetal diagnostics for any other reason, you may be offered a NIPT if the ultrasound examination during week 11-14 and the double test (CUB test) showed a higher than normal probability that the fetus has a trisomy. The offer of a NIPT through the national pregnancy care service is free of charge.

New rules from 2021

Since 1 April 2021, pregnant women have been able to have a NIPT in order to investigate whether their unborn child could have trisomy 13, 18 or 21. Pregnant women aged 35 years or over on their due date will eventually be offered a NIPT via the national health service. The current scheme will continue to apply until the new service is in place.

You will also be able to also contact a private health service provider once the service is in place.

What happens in practice?

Pregnant women who are offered NIPT via the national health service will have a blood sample taken for use in a NIPT in connection with their ultrasound examination during week 11-14.

You should not have a blood sample taken for NIPT until week 10+0 of your pregnancy. The Norwegian Directorate of Health recommends that the sample be taken during weeks 11-14, because this will improve the reliability of the result.

Who can offer NIPT?

Only service providers which possess certain qualifications and have been approved by the Norwegian Directorate of Health can take blood samples for NIPT. The sample will be sent to a laboratory, which will perform the analysis.

Only university hospitals with a department of medical genetics or a centre for fetal medicine can currently offer NIPT, but eventually local hospitals and private service providers will also be able to obtain authorisation.

An authorisation scheme has also been set up for private service providers wishing to offer NIPT.

Health professionals working for service providers which do not have authorisation are not permitted to take a blood sample from you for a NIPT and send it abroad for analysis.

Overview of authorised departments of medical genetics and centres for fetal medicine (in Norwegian):

Private services

Authorised private service providers can offer NIPT. The private service provider’s midwife or gynaecologist must first perform an ultrasound examination of you to check that your fetus is alive and determine the number and age of the fetus(es).

This is a simple procedure, not a comprehensive ultrasound examination which pregnant women entitled to fetal diagnostics have.

The service provided by private operators is not covered by the national pregnancy care service.

How long will it take to get the results of the procedure?

You will receive the results of your NIPT analysis within 10-16 days. You will be contacted in the manner you agreed with your doctor/midwife.

The midwife or doctor will explain the results to you, how certain the test results are and whether any further tests may be necessary at a later date.

In most cases, NIPT tests show no signs of trisomy in the fetus and no further tests will be necessary.

What happens next if a NIPT shows a high probability of trisomy?

In some cases, a NIPT may indicate an increased likelihood that the fetus has a trisomy. You will then normally be advised to have an amniotic fluid test in order to obtain a definitive diagnosis. Private hospitals and clinics which offer NIPT have procedures for referring pregnant women for follow-up examinations at a centre for fetal medicine.

NIPT or NIPD for other medical conditions

NIPT to determine gender

You may be offered a NIPT if there is an increased likelihood that you will have a child with a serious, hereditary gender-linked condition which mainly affects boys. In such cases, a NIPT will be performed to determine the sex of the fetus.

You will often be aware of the likelihood of your unborn child having a gender-linked condition in advance, and have been given genetic counselling before your pregnancy.

What happens in practice?

In order to be offered NIPT to determine the sex of the fetus, the midwife or doctor must refer you to a department of medical genetics or a centre for fetal medicine. Your blood sample will be analysed abroad.

The test for determining the sex of the fetus is very precise, but it cannot show whether or not the unborn child will actually have the condition.

If the fetus is male, you will therefore be offered a placenta or amniotic fluid test to find out whether or not the fetus has inherited the genetic defect concerned. A placenta or amniotic fluid test will provide a definitive answer.

If the fetus is female, no further prenatal diagnostic testing will be necessary.

NIPD for conditions linked to specific genes

You may be offered non-invasive prenatal diagnostics (NIPD) if there is an increased likelihood of you having a child with a serious hereditary condition which is linked to a particular gene.

In most cases, this will involve a genetic defect which can cause a serious disease. The genetic defect may have been detected in you or the child's father (dominant inheritance) or in both of you (recessive inheritance).

What happens in practice?

In order for you to be offered fetal diagnostics with NIPT, your midwife or doctor must refer you to a department of medical genetics or a centre for fetal medicine. You are entitled to genetic counselling before you have the procedure.

NIPD has been developed for a number of serious hereditary diseases linked to a single gene. Departments of medical genetics will know whether or not it is possible to offer you a NIPD instead of a placenta or amniotic fluid test.

The NIPD analysis normally has to be “tailored" for an individual woman or couple and should therefore be planned in advance of pregnancy.

Placenta test

A placenta test is an analysis of cells taken from the placenta. The placenta develops from the fertilized egg, and therefore reflects the DNA (genetic material) of the fetus. A placenta test can reveal whether or not the fetus has inherited a genetic defect which has caused a serious illness in either your family or your partner's family. The test can provide a definitive answer as to whether or not the fetus has trisomy 13, 18 or 21.

Who will be offered a placenta test?

You may be offered a placenta test if:

  • it has been demonstrated that there is a high probability of trisomy in the foetus
  • you already know that the fetus could have a serious, hereditary disease or condition
  • fetal abnormalities have been detected via an ultrasound examination

What happens in practice?

In order for you to have a placenta test, your midwife or doctor must refer you to a department of medical genetics or a centre for fetal medicine. You will be given guidance and information about the procedure in advance.

A placenta sample will be taken between weeks 11 and 14.

What does a placenta test involve?

Placenta tests can be performed in one of two ways:

  • through the abdominal wall (transabdominal)
  • via the vagina through the cervix (transcervical)

An ultrasound examination will first be performed to determine the most suitable method. This will depend on the position of the placenta.

Under ultrasound guidance, a needle is inserted through the abdominal wall into the placenta. A small sample of tissue will then be drawn out from the placenta.

Alternatively, a small clamp can be inserted into the placenta via your cervix and a small sample of tissue taken.

The procedure may hurt a little. Different people experience the pain in different ways, but for most people, it is similar to the pain that is experienced when a cell specimen is taken from the cervix.

After the sample has been taken, you will often be asked to wait about 15 minutes before leaving the hospital. You may be advised to take it easy for two to three days after the procedure. You will not normally need to take sick leave.

How long will it take to get the results of the procedure?

How long it takes for you to find out the results of the test will depend on what you are being tested for. You will normally be told the results within 3 to 7 days. Some analyses take longer.

You will be told how long you should expect to have to wait for your results either during your genetic counselling session or when the sample is taken. The results will be sent to you by letter or phone.

The placenta test gives an uncertain result in around two percent of cases. It may then be necessary to double-check the result via an amniotic fluid test.

Are there any risks associated with the procedure?

Up to 0.5 percent of women who have a placenta test may experience complications caused by the sampling procedure, including miscarriage. Any miscarriage will usually occur during the first week after the sampling procedure.

Amniotic fluid test

An amniotic fluid test is an analysis of cells taken from the amniotic fluid. An amniotic fluid test can reveal whether or not the fetus has inherited a genetic defect which has caused a serious illness in either your family or your partner's family. The test provides a definitive answer as to whether or not the fetus has trisomy 13, 18 or 21.

An amniotic fluid sample will normally be taken later in the pregnancy than a placenta test, from week 15+0 -16.

Who will be offered an amniotic fluid test?

You may be offered an amniotic fluid test if:

  • it has been demonstrated that there is a high risk or likelihood of trisomy in the fetus (via a CUB or NIPT)
  • you already know that the fetus could have a serious, hereditary disease or condition
  • fetal abnormalities have been detected via an ultrasound examination

In order for you to have an amniotic fluid test, your midwife or doctor must refer you to a department of medical genetics or a centre for fetal medicine.

What does an amniotic fluid test involve?

Before the amniotic fluid sample is taken, an ultrasound examination will be performed to determine both the size and position of the fetus and the best place to insert the needle.

Under ultrasound guidance, a thin needle will be inserted into the amniotic cavity. Approximately 15 ml of amniotic fluid will then be drawn out. This procedure may hurt a little, much like having a normal blood sample taken.

After the specimen has been taken, it is recommended that you wait around 15 minutes before leaving the hospital. You may be advised to take it easy for two to three days after the procedure. You will not normally need to take sick leave.

How long will it take to get the results of the procedure?

How long it takes for you to find out the results of the test will depend on what you are being tested for. You will normally get the result after 3 to 10 days. Some analyses take longer.

You will be told how long you should expect to have to wait for your results either during your genetic counselling session or when the sample is taken. The results will be sent to you by letter or phone.

Are there any risks associated with the amniotic fluid test?

Up to 0.5 percent of women who have an amniotic fluid sample taken can develop complications due to the sampling procedure, including miscarriage. Any miscarriage will usually occur during the first week after the sampling procedure.