Prenatal screening

Prenatal screening allows us to estimate the chance that your baby has certain defects. The higher the age of the mother, the higher the risk of these defects. During the first appointment, we will give you elaborate information, and we will answer your questions. It can be a difficult decision whether or not to do prenatal screening. That is why we recommend you to read some information about prenatal screening before your first appointment.

At our practice on the Scheveningseweg, we offer ultrasound imaging. You can make an appointment for a combined test and/or a 20-week ultrasound as well as for the NIPT test. This appointment can be followed by a checkup with your midwife to discuss the preliminary results.

Non-invasive prenatal test (NIPT)

DNA of the unborn child is present in the blood of all pregnant women. This knowledge was the basis of a non-invasive prenatal test that tests the DNA in the blood of the mother for chromosomal abnormalities of the child. This test is very reliable and safe. The NIPT can be done at 10 weeks pregnant and onwards. All we need is two vials of blood of the mother-to-be. The result can be normal or abnormal. An abnormal result of the NIPT could indicate the presence of the trisomy 21, 18 or 13. However, it is also possible that an abnormal result is not an indication of a baby with trisomy 21, 18 or 13. Therefore, in case of an abnormal result, to be certain, we need to do follow-up invasive tests. These tests are called a chorionic villus sampling test and amniocentesis. One of these tests is necessary to confirm the NIPT result.

Most NIPT results are normal. In case of a normal result, the chance of a baby with a trisomy is so small (smaller than 1 in a 1000) that we do not recommend to do a follow-up test. If pregnant women with a higher chance of a trisomy do the NIPT test and the result is normal, a chorionic villus sampling test or an amniocentesis are also not necessary. In 2% of women who do a NIPT test, the test fails and needs to be repeated. If the test fails a second time, a combined test, chorionic villus sampling test, or an amniocentesis is necessary.
For more information, see the folder on prenatal screening on the website of the RIVM.

As of April 1, 2017, the NIPT is the first screening test available to all pregnant women in the Netherlands. Since April 1, 2017, you can choose the NIPT test directly through the Trident 2 study. This study runs for three years. The goal of the study is to find out whether the NIPT being the first screening test available to all women in the Netherlands is desirable and cost-effective. The costs for the NIPT as part of this study are € 175,- (2019). All hospitals in the Hague take blood samples for the NIPT. Our clients can also have their blood drawn at our location on the Scheveningseweg 72.

Before doing the NIPT, you will need to make an appointment with your midwife for counseling. You will also be asked to sign a consent form to enroll in the Trident 2 study. The NIPT has to be paid in advance and you have to be at least 11+0 weeks pregnant. We need to do an ultrasound to confirm that the baby is vital. This ultrasound has to be done within a week before taking the blood sample. Before you have your blood drawn, you must show proof of payment (printed) and submit the application form for the blood sampling. We are obligated to save the original consent form for 15 years.

If you participate in the Trident 2 study, the result will not show the sex of the baby.


Age of the mother
Chance of a child with Down syndrome
20 – 25 years 1 in a 1.000
26 – 30 years 1 to 2 in a 1.000
31 – 35 years 2 to 5 in a 1.000
36 – 40 years 6 to 15 in a 1.000
41 – 45 years 20 to 61 in a 1.000


Additional findings of the NIPT

Please consider whether you want to be informed about any additional results. Beside the trisomies 13, 18 and 21, the NIPT can also detect other trisomies, deletions or duplications of the chromosomes. Such abnormalities could have serious consequences for the health of your child. Whether or not you want to be informed about any additional findings is up to you. If any of the additional results of the NIPT are abnormal, additional invasive diagnostic testing will be done to obtain certainty about the outcome. The result of the NIPT takes 10 workdays. You will get the results of the NIPT from the health practice that referred you. You cannot do both the combined test and the NIPT.

When can you participate?

You can participate in the Trident 2 study if you:

  • Have Dutch health insurance.
  • Are 18 years or older.
  • Are pregnant with a singleton or identical twins.
  • Are between 11+0 weeks and 18+6 weeks pregnant.
  • Are able to understand Dutch or can be counselled with the help of an interpreter and can answer the questions of the study.

You are excluded from the Trident 2 study if:

  • You are pregnant with fraternal twins.
  • You had a vanishing twin.
  • The ultrasound shows a fetal abnormality, e.g. an increased nuchal translucency (NT ≥ 3.5mm)
  • You or your partner have a chromosomal abnormality.
  • You have a malignant tumor at the time of your application.
  • You had a blood transfusion, stem cell or organ transplantation or immunotherapy less than 3 months ago.

Information about the screening for Down syndrome, Edwards' syndrome and Patau's syndrome

Information brochure of RIVM

Download folder

Structural Echo Examination

Information brochure from RIVM

Download folder

The combined test

The combined test is a screening test to determine the risk of Down syndrome (trisomy 21). The chance of a baby with Down syndrome increases as the age of the mother increases. The combined test gives an estimation of the risk, based on the specific characteristics of your pregnancy. The reliability of this test is about 85%.

If you participate in the screening for Down syndrome, you can also request the results of the screening for other chromosomal abnormalities: trisomy 13 (Patau syndrome) and 18 (Edwards syndrome). Both disorders are chromosomal defects that cause severe physical and mental disabilities.

The combined test does not carry any risks for the mother or the child. Depending on the results of the test, you (and your partner) have to make a decision whether or not you want to do follow-up tests. If you choose to do the combined test, you will have to pay for the test yourself. Since 2015, this also applies to women older than 36. The costs for the combined test are € 170,13 (2019).

Two tests

The combined test consists of two different tests:

  • The maternal serum screening test is a blood test for pregnant women. This test determines the levels of 2 substances (PAPP-A and free β-hCG). The levels found in this blood test are compared to those of women of the same age and weight and with the same smoking habits. This test can be done between 9 and 14 weeks pregnant./li>
  • A nuchal translucency measurement (or NT-scan) measures the amount of fluid that can be seen in the nuchal fold of a fetus between 11 and 13 weeks old. Abnormal levels in the blood test or a thicker nuchal fold could indicate an increased risk of a child with Down syndrome.

By combining the results of both tests, a personalized risk assessment can be made.
Based on the results of these tests, you can find out whether you have an increased or a low risk of having a baby with Down syndrome.

Increased risk

We speak of an increased risk, if the chance of your child having Down syndrome (or one of the other two syndromes) is 1 in 200 (0.5%) or higher.

If the results of the combined test show that there is an increased risk of your child having the trisomy 21, 18 or 13, then the costs of follow-up tests (NIPT, chorionic villus sampling test or amniocentesis) will be covered by your insurance. These costs will be subtracted from your deductible.

Please contact your insurance company for more information on the coverage of costs of prenatal screening.

Before the first consultation

We would appreciate it if you could read the information on either of the following websites before your first consultation: (in Dutch) or (in English)

If you do not have a Dutch health insurance or cannot participate in the Trident 2 study due to the criteria stated above, you could, in accordance with your midwife and depending on the exclusion criteria, still do the NIPT test through Gendia. You would have to pay for the test yourself. The costs are €450 (2019). You could also do the combined test. The costs for this test are €170 (2019). These costs are also for your own expense. If the result of the combined test is an increased risk of the trisomy 21, 18 or 13, you could do the NIPT as part of the Trident 1 study.

The SHL-group (a collective of health care professionals) takes the blood samples for the NIPT for Gendia and also for the NIPT as part of the Trident 2 study. The SHL group does so at our midwifery practice on the Scheveningsweg. We will not charge you for this service. The blood sampling is only done for pregnant women, who are registered at our midwifery practice. The costs for the NIPT still need to be paid.

For more information: (In Dutch)

Invasive diagnostic techniques

Invasive diagnostic techniques are necessary if the NIPT result is abnormal (meaning an increased risk of a child with the trisomy 21, 18 or 13) in order to provide 100% certainty about the test result. An amniocentesis will take place between 16 and 17 weeks pregnant and a chorionic villus sampling test will be done between 11 and 13 weeks pregnant.

Both chorionic villus sampling and an amniocentesis carry a slight risk of miscarriage. This risk is 2 in a 1000 pregnancies.

Risk assessment

Based on the information that you give us during the first appointment, we will do a risk assessment. If you appear to have an increased risk of having a baby with birth defects, we will discuss several possible tests with you. You could have an increased risk if you are older than 36, or if a previous child or other family members of the parents have (genetic) abnormalities.

If you appear to have an increased risk of a child with a birth defect , we will discuss the tests with you that could determine the chances of abnormalities more accurately. Until the 1st of January 2015, pregnant women older than 36 were always allowed to do invasive follow-up tests (amniocentesis and chorionic villus sampling test), but this is no longer possible. If you are older than 36, you can choose to do the combined test or the NIPT, just like women who are younger than 36.

The 20-week ultrasound

Between 18 and 22 weeks pregnant, you can decide to have a 20-week ultrasound. This ultrasound will show any visible physical abnormalities. A specially trained ultrasound technician will do this ultrasound with an advanced ultrasound machine.

A 20-week ultrasound can be done in our midwifery practice. Your insurance company will cover the costs of the 20-week ultrasound. The goal of the 20-week ultrasound is not specifically to detect trisomies, but to detect physical abnormalities that correspond to certain trisomies or other genetic diseases. If such abnomalities are detected, invasive diagnostic techniques could provide more (accurate) information.

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