Prenatal diagnosis is a range of tests and examinations that provide information about the fetus. The vast majority of babies are born healthy, but ultrasound, CUB, NIPT, amniocentesis and placenta tests can tell you if the fetus has certain abnormalities or diseases.

Prenatal diagnosis is a collective term for various examinations and tests that can be performed during pregnancy to detect various fetal abnormalities. Prenatal diagnosis can provide information about abnormalities in the fetal organs or genetic material. Current ultrasound technology can detect many organ abnormalities, but not all. Together with genetic analysis, we can find out the genetic makeup of the fetus.

The reasons why people choose to undergo prenatal diagnosis vary. Some have a family history of hereditary diseases and want to see if the fetus carries this disease, while others are concerned and want to prepare by gathering as much information as possible. The important thing is to decide how to deal with the result. Can you accept a probability calculation, or are you a person who needs a 100% answer? What would you do if a chromosomal and/or organ abnormality was detected?

All forms of prenatal diagnosis are completely voluntary in Sweden and it is ultimately the pregnant woman's choice as to how she views the results.

The majority of all babies born are healthy. Only around 2% are born with some form of organ malformation or chromosomal abnormality. The most common chromosomal abnormality is trisomy 21, better known as Down syndrome. You are always entitled to both oral and written information about prenatal diagnosis, ranging from the possibilities that prenatal diagnosis can offer, to the limitations and risks that the abnormality may entail. Each region has its own guidelines on the type of prenatal diagnosis offered.

Prenatal diagnosis - what tests can be done?

Many people wonder what methods are used for prenatal diagnosis. Apart from routine ultrasound, which is offered to everyone in Sweden, it is common to perform prenatal diagnosis via KUB, but there are also other options.

- Routine ultrasound is usually carried out by a midwife and takes place around 19-20 weeks of pregnancy and shows, for example, how long a pregnancy has lasted. If you have not received a date according to ultrasound at the time of any KUB, your estimated date of delivery is set now. The routine ultrasound also shows how many fetuses there are in the uterus, organ screening is performed, the placenta is checked, amniotic fluid is measured and fetal movements are recorded.
- KUB is a combined ultrasound and blood test of the pregnant woman. It calculates the probability of Down syndrome and two other chromosomal abnormalities. KUB can be done between weeks 11+0-13+6. The test does not increase the risk of miscarriage.
- NIPT involves taking a blood sample from the pregnant woman from week 10+0 (week 11 of pregnancy). This allows you to see any abnormalities in the chromosomes of the fetus with high reliability. If you don't know exactly what week you are in (i.e. you haven't had IVF or an early ultrasound), an ultrasound is also needed to determine the length of your pregnancy. The sample will then be sent for analysis and you may get results for more chromosomes than those included in the KUB test. The test does not increase the risk of miscarriage.
- Amniocentesis is offered, for example, if any of the above methods have shown an increased likelihood of a genetic abnormality in the fetus or if one of the parents carries a hereditary disease. Together with placenta tests, these tests are the most reliable (almost 100%), and are called invasive testing. A thin needle is inserted into the uterus and a sample of amniotic fluid is taken and sent for analysis. The sample takes about two weeks to be analyzed. Amniocentesis is done at the earliest in week 15+0. There is a small increased risk of miscarriage*.
- Placenta sample is 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. The test takes about two weeks to get a result. There is a small increased risk of miscarriage*.

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

Curious about the placenta? Read more here!