If the fetal screening result indicates an increased risk of developmental disorders, the parents decide whether they want further investigations. The fetal structures can be examined with a more detailed ultrasound and, sometimes, an MRI. Chromosome analysis can be done on a sample from the placenta or amniotic fluid. These tests carry a small miscarriage risk of less than 1%.
Placental sampling can be done after the 10th week of pregnancy. A sample is taken through the abdominal wall and uterine wall with a needle. The needle is inserted into the area of the placenta under ultrasound guidance, from which a small amount of placental tissue is obtained into a syringe. Results can take from a few days to 3–4 weeks.
Amniocentesis is usually performed between the 15th and 16th weeks of pregnancy. An amniotic fluid sample is taken through the abdominal wall with a needle under ultrasound guidance, and a small amount of amniotic fluid is extracted. Results are available within 2–3 weeks.
Mothers in the risk group are offered the option to participate in a second, more accurate screening based on fetal-derived DNA in the mother’s blood (NIPT) as an alternative to chromosome analysis. This test does not carry a miscarriage risk. NIPT testing sensitively detects the most common fetal chromosomal abnormalities, including trisomies 13, 18, and 21.
Follow-up actions if the test results are abnormal
If fetal screening suggests a heart structural abnormality, the expectant mother is referred to a specialized cardiologist at the New Children’s Hospital for fetal evaluations. If the parents choose, it is possible to seek pregnancy termination due to a severe developmental disorder or defect up to the 24th week of pregnancy. If the pregnancy is continued, arrangements are made for monitoring, delivery, and any necessary postnatal care in the best possible way. For more severe heart defects, deliveries are planned to take place in Helsinki to ensure immediate care for the newborn.