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Additional resources
If you want to learn more about this topic, here are some resources that could be useful to you for making your decisions:
FAQ
Q: What is a risk factor?
A: According to the World Health Organization (WHO), a risk factor is any attribute, characteristic, or exposure of an individual that increases the likelihood of developing a disease or sustaining an injury. For example, a woman's age at conception is one of the attributes that increase the likelihood of having a child with trisomy 21, 18, or 13.
Q: What are the other risk factors for trisomy 21, 18, or 13?
A: Genetics, diet, lifestyle, and environmental factors can increase the likelihood of having a child with a trisomy. However, the main probability factor is the advanced age of the mother at the time of conception. The probability of carrying a fetus with a trisomy increases proportionately with increasing maternal age after 35. In fact, more errors occur during the development of an ovum among women over 35 years of age. Maternal risk factors account for about 88% of trisomy cases.
Q: Why wasn't I offered the same screening as my friend/colleague/sister/acquaintance?
A: The offer of screening varies depending on your risk profile. Women with a low risk profile will be offered the biochemical test as their first screening test. Women with a high risk profile (previous pregnancy with a baby with trisomy 21, 18, or 13; maternal age greater than or equal to 40 years at the time of delivery) will be offered the non-invasive prenatal testing as their first and only screening test.
Q: Why don't I have a result for my non-invasive prenatal testing (NIPT)?
A: It is possible for a non-invasive prenatal testing result to be uninterpretable. There are several reasons why the result may not be interpretable: the conditions under which the blood sample was collected, transported, or stored; the sample itself (e.g., fetal DNA fraction too low, sample collected too early); the mother (e.g. maternal obesity); and amplification or sequencing errors. It is also possible for the result to be indeterminate, making it impossible to clearly establish a positive or negative result.
Q: What happens when I do not have a result for my non-invasive prenatal testing (NIPT)?
A: Given the short time frame for decision-making, amniocentesis will be offered if the non-invasive prenatal genomic test fails. This is because the likelihood of the non-invasive prenatal testing working on a repeat is low when the test failure is due to a technical problem.
Q: What should I do after a positive diagnostic test?
pregnancy. You must decide whether to continue with or terminate the pregnancy. To help you make this decision, we recommend that you discuss with your spouse, if applicable, and the health care professionals who support you.
Q: If I decide to proceed outside of the Québec Prenatal Screening Program, will the costs incurred for the tests be covered by my insurance?
A: Depending on your insurer, some or all of the costs incurred for prenatal screening tests in private clinics may be covered. We recommend that you check with your insurance company.
Q: Do screening tests detect other health conditions?
A: All screening tests can detect many other conditions besides trisomy 21, 18, and 13.
Q: Will I be given information about other conditions detected?
A: In the public health care system, in addition to your probability of having a child with trisomy 21, 18, or 13, your results report will indicate any other "abnormal" results. In the private health care system, in addition to your probability of having a child with trisomy 21, 18, or 13 and any other "abnormal" results, your report may provide additional information.
Test comparison: what happens after each test?
The top circle shows a population of 100,000 pregnant women being screened. The colours indicate the distribution of screening test results between low and high probability. The bottom two circles take these results and compare them with actual occurrences. The circle on the left shows the low probabilities and, of these, the number of pregnant women who do not actually have a fetus with one of the three types of trisomy being sought. The circle on the right shows the high probabilities and, of these, the number of pregnant women who actually have a fetus with one type of trisomy.
Total
Low probability
High probability
High probability
Low probability
No case of trisomy
Cases of trisomy
Results after the biochemical test
- The results of your screening testwill show a low or high risk that your baby has a trisomy. They only show probability, so if your probability is low, this is no guarantee that your baby does not have trisomy. By the same logic, if your probability is high, your baby does not necessarily have trisomy.
- The diagnostic test shows that:
- of the 86 706 women with a low probability result, 86 691 women are actually carrying a fetus without trisomy 21. Therefore, the biochemical testfailed to detect 15 fetuses carrying trisomy 21
- among the 13 294 women with a high probability result, 110 women are actually carrying a fetus with trisomy 21.
- of the 86 706 women with a low probability result, 86 691 women are actually carrying a fetus without trisomy 21. Therefore, the
- In total, the biochemical testmakes it possible to detect 110 of the 125 cases of trisomy 21.