Prenatal diagnosis are different tests and examinations that provide information about the foetus. The vast majority of children are born healthy, but with an ultrasound, CUB, NIPT, amniocentesis and placenta examination, you can find out if the foetus has certain abnormalities or diseases. Here, we go through the various options available from prenatal diagnosis

Prenatal diagnosis is a collective name for various examinations and tests that can be done during a pregnancy to detect various foetal abnormalities. Prenatal diagnosis can provide you with information about abnormalities in foetal organs or hereditary issues. With today’s ultrasound technology, it is possible to detect many organ abnormalities, but not all. Together with genetic analysis, we can find out the genetic make-up of the foetus.

The reasons why you may choose this vary. Some families have hereditary diseases and want to see if the foetus is carrying one, while others are worried and want to prepare by gathering as much information as possible. The important thing is to decide how you handle the results. Are you able to accept a probability calculation, or are you a person who needs a one-hundred-percent answer? What would you do if a chromosomal and/or organ abnormality were discovered?

All forms of prenatal diagnosis are completely voluntary in Sweden and it is ultimately the pregnant person’s choice as to how they react to the results.

The majority of all children born are healthy. Only about 2% are born with some form of organ malformation or chromosomal abnormality. The most common chromosomal abnormality is trisomy 21, better known as Down’s Syndrome. You always have the right to both oral and written information about prenatal diagnosis when you go to your antenatal clinic. The information contains everything from the possibilities that prenatal diagnosis can offer, to the limitations and risks that the possibly discovered deviation can entail. All regions have their own guidelines regarding the type of prenatal diagnosis offered.

There are various prenatal diagnostic examinations:

• Routine ultrasound (RUL) is usually performed by a midwife and takes place around weeks 19-20 and shows, for example, how far along a pregnancy is. If you have not received a due date from an ultrasound at a CUB, your estimated delivery date will now set during the routine ultrasound. The routine ultrasound also shows how many foetuses there are in the uterus, organ screening is performed, the placenta is checked, the amount of amniotic fluid is measured and foetal movements are recorded.
• CUB is a combined ultrasound and blood test from the pregnant person. The probability of Down’s syndrome and two other chromosomal abnormalities is calculated at this point. A CUB can be done between weeks 11+0 and 13+6. The test does not involve an increased risk of miscarriage.
• NIPT involves taking a blood sample from the pregnant person at week 10+0 (pregnancy week 11). It is possible to see with high reliability any abnormalities in the foetal chromosomes. If you do not know exactly what week you are in (i.e. if you haven’t had IVF or an early ultrasound), an ultrasound is also needed to determine the length of the pregnancy. The sample is then sent for analysis and you may get results for more chromosomes than those included in the CUB test. The test does not involve an increased risk of miscarriage.
• Amniocentesis is offered, for example, if one of the above methods has shown an increased likelihood of genetic foetal abnormality or if one of the parents carries a hereditary disease. Together with placenta samples, these tests are the most reliable (almost 100%), and are called invasive sampling. A thin needle is inserted into the uterus and takes a sample of the amniotic fluid, which is then sent for analysis. It takes approximately two weeks to receive an answer from this test. Amniocentesis is done at week 15+0 at the earliest and entails a slightly increased risk of miscarriage.
• Placenta tests are an alternative to amniocentesis. Placenta tests can be done from week 11+0, but may need to be done later depending on the location of the placenta. The process is similar to that of amniocentesis, but the sample is taken from the placenta. It takes approximately two weeks to receive an answer from this test. Entails a slightly increased risk of miscarriage.

The increased risk of miscarriage with invasive sampling is estimated to be less than 1/200.