The Québec Prenatal Screening Program aims to make prenatal screening for trisomy 21, trisomy 18 and trisomy 13 accessible to pregnant people and couples in Québec on a voluntary basis.
The Québec Prenatal Screening Program is offered free of charge in the public health network.
By participating in this program, you will be able to find out as early as possible during your pregnancy if your baby or, in the case of a twin pregnancy, your babies have a high probability of having one of the trisomies screened for.
If the probability is high, additional tests will be offered to confirm whether the baby or babies have the trisomy. If so, you may have to decide if you want to continue your pregnancy or terminate your pregnancy.
There are chromosomal abnormalities other than the three trisomies but they are not screened by the public program, which is based on Canadian recommendations.
The Québec Prenatal Screening Program is offered during pregnancy follow-up but it is not a routine test. You decide whether to participate. This decision and the reasons behind your choice are entirely yours. You can choose whether to have the screening tests based on your situation, desires and values. Moreover, at any time, you can decide to withdraw from the program if you want.
Deciding whether to participate in the Québec Prenatal Screening Program is not necessarily easy. Don’t hesitate to talk to the professional who is monitoring your pregnancy about it. For a clearer understanding, you could also ask yourself the following questions:
- Do I want to know my probability of having a baby with trisomy 21, trisomy 18 or trisomy 13?
- How will I react if the result of the screening tests is showing a high probability of trisomy?
- Do I want to have amniocentesis if the result of the screening test is showing a high probability of trisomy, despite the risk of a miscarriage?
- Do I want to terminate my pregnancy if I find out my baby has trisomy 21, trisomy 18 or trisomy 13?
- Do I want to continue my pregnancy if I find out my baby has trisomy 21, trisomy 18 or trisomy 13, and raise my child or, alternatively, give my child up for adoption?
The professional who is monitoring your pregnancy, whether it is a doctor, a midwife or a specialized nurse practitioner, must ensure that you have received all the information needed to make the decision on whether to participate in the program.
Regardless of your decision, you will have to sign a form indicating your choice. The professional providing your pregnancy follow-up will answer your questions and help you through the process.
Trisomy 21, also known as Down Syndrome, is caused by the presence of an extra chromosome in the 21st pair of the 23 pairs of chromosomes found in every human cell. It is one of the most common trisomies. It is not generally hereditary (more than 95% of cases) and therefore occurs at random. Less than 5% of cases are inherited.
All people with trisomy 21 have some degree of intellectual disability, varying from mild to severe. Some people may need a lot of support and guidance throughout their life, while others may have a job and lead an almost independent life. The level of autonomy and intellectual functioning that a child with trisomy 21 may develop are impossible to determine in advance.
Most children with trisomy 21 can walk and talk, but it takes longer for them to learn language and motor skills. The interventions and support these children receive from an early age influence their development. In addition to intellectual disability, these children may have other types of health problems, such as heart and bowel malformations or epilepsy.
People with trisomy 21 have the potential to establish deep emotional relationships and lead lives that are fulfilling both for themselves and their loved ones.
Frequency of trisomy 21
Around 1 in 800 babies is born with trisomy 21. Any pregnant woman, regardless of her age, may be carrying a child with trisomy 21. However, the probability increases with age.
The graph below shows that the probability of carrying a child with trisomy 21 increases with the person's age. At age 20, the probability is 1 in 1,528 pregnant women, while at age 45, the probability increases to 1 in 28 pregnant women.
Trisomy 18, also known as Edwards syndrome, is caused by the presence of an extra chromosome in the 18th pair of the 23 pairs of chromosomes found in every human cell. It is the most common trisomy after trisomy 21.
Trisomy 18 remains rare and affects 1 in 4,500 babies at birth. However, nearly 95% of pregnancies in which the baby has trisomy 18 end in miscarriage or the baby’s death before birth. Any pregnant person can have a baby with this chromosomal abnormality, but the probability increases with age. Trisomy 18 occurs randomly in most cases.
People with trisomy 18 have stunted growth before and after birth. They have an intellectual disability and severe global developmental delay. Most of these people have abnormalities of the hands and feet. Major malformations of internal organs, particularly the heart and kidneys, are common. Most babies born with trisomy 18 die shortly after birth due to severe heart and brain malformations or respiratory disorders. Only 5 to 10% survive beyond a year. However, in exceptional cases, some babies reach adulthood. In all cases, babies who have trisomy 18 will receive support and comfort care or may receive some treatment, depending on the symptoms.
Trisomy 13, also known as Patau syndrome, is caused by the presence of an extra chromosome on the 13th pair of the 23 pairs of chromosomes found in every human cell.
Trisomy 13 affects 1 in 7,000 babies at birth. It is very severe and often associated with a miscarriage or multiple malformations. Over 95% of affected babies die before birth. Of the pregnancies carried to term, half the babies will die during the first month of life and 90% will die before one year from cardiac, kidney and neurological complications. In exceptional cases, the baby may live longer if it does not have any major brain malformations. Any pregnant person can have a baby with this chromosomal abnormality, but the probability increases with age.
Trisomy 13 is characterized by facial abnormalities and limb deformities, very severe neurological problems and brain, heart and urogenital malformations. Intellectual and developmental delays are severe.
Generally, medical care is limited to providing support and comfort care.
Eligibility and cost
The Québec Prenatal Screening Program is offered free of charge to anyone who is pregnant with one or two babies and has a Régie de l'assurance maladie du Québec (RAMQ) health card. Some people with special status may also have access to it.
People with multiple pregnancies, who are carrying three or more babies, are not eligible for the Québec Prenatal Screening Program due to its current limitations. They need to speak with the professional monitoring their pregnancy to find out about the options available to them.
Access to NIPT for people pregnant with twins
Since April 3, 2023, people pregnant with twins have been eligible for non-invasive prenatal testing (NIPT). Access to this test is gradually being offered at health and social services institutions in Quebec. To find out when this test will be offered in your region, please consult the professional who is monitoring your pregnancy.
The Québec Prenatal Screening Program includes:
- a biochemical component, which includes taking two blood samples;
- the nuchal translucency measurement, when possible;
- non-invasive prenatal screening testing (NIPT).
You can end your participation at any stage of the program.
The prenatal screening steps diagram illustrates the moments in the process when you will have to make a decision.
First trimester ultrasound
You will be offered a first trimester ultrasound between the 11th and 14th weeks to check how far along you are in your pregnancy and identify possible abnormalities in your baby or babies. This ultrasound is used to assess how long you have been pregnant in order to calculate the probability of having a baby with a trisomy. This ultrasound will also determine whether there is one or more babies.
Biochemical test results (with or without nuchal translucency)
Whether or not it is combined with the nuchal translucency measurement, the biochemical test is a screening test used to calculate the probability (high or low) that you are expecting a baby with trisomy 21. As part of this test, a similar calculation of probability is done for trisomy 18. At this stage, it is not possible to distinguish between trisomy 18 and trisomy 13.
The biochemical test allows us to analyze the baby’s proteins or hormones present in the blood of the pregnant person.
This test is not available to people pregnant with twins.
The biochemical test involves having two blood tests during your pregnancy:
- the first blood test is done between weeks 10 and 13;
- the second blood test is done between weeks 14 and 16.
Both blood tests are important and ensure more reliable results than a single blood test. It is therefore preferable to have the two blood tests done at the right time if you decide to participate in the Québec Prenatal Screening Program. There is no risk for the pregnancy associated with the blood tests.
Nuchal translucency measurement
The nuchal translucency measurement might be offered to you. It is performed between weeks 11 and 13, during an ultrasound. It measures the thickness of the fluid build-up at the back of the baby’s neck. In babies with trisomy 21, the nuchal translucency is often thicker than normal.
The nuchal translucency measurement is not available in all institutions in the public network. When it is performed in a private clinic, you may be able to recover expenses.
Biochemical test results (with or without nuchal translucency)
The results of the two blood tests and nuchal translucency measurement, when available, will indicate whether the probability of trisomy 21 is low or high.
Low probability (less than 1 in 300)
It is unlikely that your baby has trisomy 21. Therefore, no additional tests are necessary (more than 95% of women get this result when they have the biochemical test).
A low probability does not guarantee that your baby does not have trisomy 21. Considering the natural differences between individuals and the limitations of prenatal screening, the blood tests and nuchal translucency measurement cannot detect all cases of trisomy 21.
High probability (equal to or higher than 1 in 300)
You may be carrying a child with trisomy 21 (3 to 4% of women get this result when they have the biochemical test). A follow-up appointment will be offered to confirm the presence of trisomy 21. A high probability does not necessarily mean that the baby has trisomy 21.
As part of this test, a similar calculation of probability is done for trisomy 18. At this stage, it is not possible to distinguish between trisomy 18 and trisomy 13.
At this point, the professional who is monitoring your pregnancy will recommend that you move on to the next stage of the program. That’s your decision.
If the results of the previous tests show that there is a high probability that your baby has one of the screened trisomies, the health professional monitoring your pregnancy might offer you the non-invasive prenatal screening testing (NIPT) or that you go straight to amniocentesis. You will be given the explanations and information you need to decide which option is best for you.
Non-invasive prenatal screening testing (NIPT)
Non-invasive prenatal screening testing (NIPT) involves taking a sample of the pregnant individual’s blood to analyze DNA fragments from the placenta.
The NIPT screens for trisomy 21, trisomy 18 and trisomy 13.
This test is offered because it is reliable and safe. There is no risk of miscarriage compared with amniocentesis.
The NIPT might be recommended right away instead of the biochemical test if you are in one of the following situations:
- you have had a pregnancy in which the baby had trisomy 21, trisomy 18 or trisomy 13;
- you will be 40 years old or older at the time of delivery;
- you are pregnant with twins (two foetuses);
- the test is prescribed following a consultation in genetic medicine.
Non-invasive prenatal screening test results
The lab provides the results in 5 to 10 days following receipt of your blood sample.
In the case of a pregnancy with twins, the NIPT results do not indicate whether the results apply to one or both babies. Therefore, the results provided concern both babies without distinction.
There is a very low probability that your baby has one of the screened trisomies, even if the result of the biochemical test showed a high probability initially. This result is over 99% reliable. There is no need for further investigations.
It is likely that your baby has one of the three screened trisomies. However, this result is not 100% certain an only a diagnostic test (amniocentesis) can determine with great certainty whether your baby has one of these trisomies.
Limitations of non-invasive prenatal screening testing
- does not identify all babies with one of the screened trisomies;
- does not eliminate the possibility of a false positive. In fact, there is a low possibility that the baby does not have one of the three trisomies, even if the result is positive. For this reason, amniocentesis is offered in the event of a positive result;
- does not work in a small percentage of women. In this situation, the health professional who monitoring your pregnancy can talk to you about your options, in particular amniocentesis;
- does not screen for all genetic diseases that cause abnormalities, intellectual delays or autism.
Amniocentesis is a diagnostic test that will be recommended to you if the NIPT results show a high probability for trisomy 21, trisomy 18 or trisomy 13.
Amniocentesis can confirm with great certainty whether your baby has one of the three screened trisomies, and it can confirm with the same certainty whether your baby does not have one of these trisomies.
In the case of a pregnancy with twins, amniocentesis can confirm with great certainty whether both babies have a trisomy or which of the two babies has a trisomy, if any.
Some people may want to go straight to amniocentesis without doing the genomic test, despite the risks involved. This possibility can be discussed with the professional responsible for monitoring your pregnancy.
Amniocentesis involves inserting a fine needle into your abdomen to collect a small quantity of the amniotic fluid surrounding the baby in the uterus. This liquid contains the baby’s cells and the chromosomes in these cells can then be analyzed. The test can be performed starting on week 15 of the pregnancy.
Following the procedure, the medical staff will give you instructions for the days following the amniocentesis.
Possible complications associated with amniocentesis
Amniocentesis carries risks for the pregnancy, the main one being miscarriage. There is about one miscarriage for every 500 amniocentesis tests, which is a risk of 0.02%. Therefore, the test is offered only to pregnant persons with a high probability result on the screening test.
Some minor complications have also been observed. The most common (2 to 5% of cases) are:
- loss of a small amount of amniotic fluid;
- uterine contractions;
- abdominal pain.
The lab can provide the results in about three days following receipt of your sample.
Absence of trisomy
Your baby does not have trisomy 21, trisomy 18 or trisomy 13. This result is the most reliable.
Presence of trisomy 21
Your baby has trisomy 21. This result is the most reliable.
You must then decide if you wish to:
- continue your pregnancy and prepare to be the parent of a child with trisomy 21;
- continue your pregnancy and place the child for adoption;
- terminate your pregnancy and deal with the grief that may cause.
The decision must be made when there is no way to predict the severity of the intellectual disability or the level of autonomy your child might have and without knowing if your child has physical malformations or will have other health problems.
Presence of trisomy 18 or trisomy 13
Your baby has trisomy 18 or trisomy 13. This result is the most reliable.
You must decide if you wish to continue or terminate the pregnancy.
The decision must take into consideration the severity of the malformations associated with these trisomies and the fact that 90% of affected newborns will not live longer than a year. The decision must also be made when it is impossible to predict with certainty the condition of your baby at birth.
Making a decision in the case of a trisomy diagnosis
Deciding to terminate or carry a pregnancy to term knowing that the baby has a trisomy is not necessarily easy.
If the outcome of your participation in the program means that you have to make a choice between continuing or terminating your pregnancy, you might need help.
The professional who is monitoring your pregnancy can direct you to psychology services to support you in your reflection. Don’t hesitate to discuss this choice with that professional, your loved ones or a genetics specialist. You can also contact groups for parents who have a child with a trisomy. This might help you to make the decision that’s right for you.
For the contact information of groups in your region, ask the professional who is monitoring your pregnancy or contact the following provincial organizations:
Maison Anne et Charles de Gaulle — Centre national de la Trisomie-21
Regroupement pour la Trisomie 21
1A-3250 Saint-Joseph Blvd East
Montréal, Quebec H1Y 3G2
Quebec Intellectual Disability Society
3958 Dandurand Street
Montréal, Quebec H1X 1P7
Canadian Down Syndrome Society
#283-5005 Dalhousie Drive NW
Calgary, Alberta T3A 5R8
Last update: April 3, 2023