Like many expectant parents, you may be concerned about the health of your (unborn) child and want to obtain as much information as possible during the course of the pregnancy.
Perhaps the pregnancy has been classified as a "high-risk pregnancy". Maybe your OBGYN detected some abnormalities during the routine prenatal care. Or further tests are recommended to you based on your family history.
Whatever the reason, you may be thinking about having additional prenatal tests to get more information.
Prenatal diagnostics refers to prenatal examinations that provide information about certain diseases, chromosomal and genetic conditions and disabilities of the unborn child. There are non-invasive and invasive examination methods, which we will introduce in this article with the help of midwife Amelie Suermann.
Amelie is a Berlin-based midwife with a Master of Science degree in Global Health. She works as one of the English-speaking midwives at Praxis Hebammenzeit in Friedrichshain. Amelie just become a mom for the second time!
Non-invasive tests
Non-invasive examinations do not interfere with the woman's body and therefore do not pose a risk to the unborn child.
However, it should be noted that non-invasive tests do not deliver a diagnosis, but rather a probability of a condition expressed in numbers (e.g. 1:250), which can be present, but does not have to be. The only way to get a diagnosis is via an invasive test (see below).
Ultrasounds
You will be offered at least three in the course of your pregnancy: in weeks 9-12, weeks 17-20, and weeks 19-32.
After the second ultrasound, your OBGYN may recommend an additional, more thorough ultrasound called “Feindiagnostik” in German or anatomy scan in English. This would happen between the 19th and 23rd week of pregnancy. During this ultrasound, they would look at the baby's organs closely to make sure everything is okay. You can learn about Feindiagnostik here.
In addition, further special ultrasound examinations are performed by prenatal physicians for certain questions:
Doppler ultrasound: to check the blood flow to the uterus and placenta, umbilical cord and important vessels of the child.
Echocardiography: more detailed examination of the fetal heart, i.e., function of heart valves and blood flow in the heart.
3D ultrasound: Many individual ultrasound slice images of the baby are combined to form a whole, three-dimensional image.
4D ultrasound: The three-dimensional image of the baby is displayed in real time, so that baby movements are instantly visible.
Nuchal translucency scan
During a special ultrasound examination in pregnancy week 12-14, the so-called nuchal translucency of the unborn child is measured. This is an accumulation of fluid in the area of the child's neck, which is normal to a certain extent, but can be an indication of a chromosomal condition and/or an abnormal development of the unborn child if it increases in size.
The main question that a nuchal fold measurement should clarify is the likelihood of a chromosomal condition in your child - that is, a difference of the number of chromosomes in a child‘s DNA.
These chromosomal conditions include mainly:
Trisomy 21 (Down syndrome),
Trisomy 13 (Pätau syndrome) and
Trisomy 18 (Edwards syndrome)
This test is called “Nackenfaltenmessung” in German and costs between €30 and €200, although some public health insurance companies pay for parts of it. If you have what is considered a high-risk pregnancy, the test will be covered by your public health insurance.
First Trimester Screening
The nuchal translucency scan (see above) is often combined with a blood test as part of the “Ersttrimesterscreening” (First Trimester Screening).
The maternal blood values, maternal age, and nuchal translucency values are correlated to provide a risk assessment for chromosomal abnormality in the unborn child.
This test is not usually covered by public health insurance, and will cost around €120-200.
However, if you have what is considered a high-risk pregnancy, the test will be covered by your public health insurance.
Molecular genetic blood tests / non-invasive prenatal tests (NIPT)
In the molecular genetic blood test, blood is taken from the pregnant woman, so that DNA of the unborn child can be extracted and analyzed for certain chromosomal characteristics. It can detect with a high degree of certainty the presence of trisomy 21, 18 and 13 as well as changes in the sex chromosomes. The findings are evaluated together with the findings from the ultrasound examination for assessment.
The tests can be run from the 10th week of pregnancy and should only be used in pregnant women with an increased risk of chromosomal maldistribution and in women with an abnormal first trimester screening result.
As of July 2022, the test may be covered by public health insurance companies if the pregnant person has had an abnormal first trimester screening result or if the doctor determines that the test is necessary due to the pregnant person’s personal situation.
Otherwise, you will have to pay for the test privately, around €120-300.
Invasive prenatal tests
Invasive prenatal examinations intervene in the woman's body by taking tissue samples of the developing placenta, amniotic fluid or fetal blood. Unlike the non-invasive screenings, these tests enable a direct examination of the child‘s genome and can be used to confirm or diagnose the presence of a trisomy or other genetic conditions.
There are various methods available for invasive examinations, depending on the stage of pregnancy and the question that is meant to be answered. Here is a summary of them:
Chorionic villus sampling
For this test, fetal cells are taken from the developing placenta through the abdominal wall with a thin needle to search for chromosomal abnormalities and hereditary diseases, among other things.
Chorionic villus sampling is performed around the 12th-13th week of pregnancy.
The risk of miscarriage is about 0.5-1%.
Amniocentesis (amniotic fluid test)
For the amniotic fluid test (Fruchtwasseruntersuchung in German), 8-10ml of amniotic fluid containing cells of the child are taken through the abdominal wall with a thin needle. The cells are examined for chromosomal abnormalities. In addition, the value of a specific protein, alpha-1-fetoprotein, is determined, which, when increased, can be an indication of certain diseases in the child.
Amniocentesis is usually performed in the 15th-18th week of pregnancy.
The risk of miscarriage after amniocentesis due to amniotic fluid leakage, infection or bleeding is between 0.2 and 1%.
Umbilical cord puncture (chordocentesis, fetal blood sampling)
In special situations, fetal blood is taken from the umbilical cord for examination for hereditary diseases, blood diseases or infectious diseases.
Umbilical cord puncture (or Nabelschnurpunktion in German) is performed from the 18th week of pregnancy. If diagnosed, the unborn child may be given medications or blood transfusions through the umbilical cord vein.
There is a risk of complications of between 1% and 3%, this decreases with increasing duration of pregnancy.
For some guidance around how to decide whether to do these tests or not, check out our follow-on article "Prenatal Diagnostics: How to Decide Whether to Test or Not."
Sources:
BZgA-Broschüre "Pränataldiagnostik - Informationen über Beratung und Hilfen bei Fragen zu vorgeburtlichen Untersuchungen"
https://www.pnd-beratung.de/was-ist-praenataldiagnostik/
