Pregnancy Trisomy 21 Screening

Our today topic is trisomy 21 risk normal range.We will talk about trisomy 21 risk normal range.What is the trisomy 21 risk normal range?Trisomy 21 Risk Normal RangeIn Quebec, the trisomy 21 screening test is offered free of charge by the Quebec Prenatal Screening Program for trisomy 21 to all pregnant women. Your health professional will tell you about it during your first pregnancy visit . However, you do not have to submit to it. This choice is entirely up to you and your spouse.What do you think When To Take Childbirth Classes ?

If you are not sure if you want to do this test, talk to your spouse, family, health care provider, or other relatives. It is important that you consider the emotional aspect of this screening test so that your decision is in line with your values, beliefs and personal experiences.

Trisomy 21 Risk Normal Range

Here are some ideas that could help you make a decision:

Is it important for me to know the probabilities of having a baby with trisomy 21?
What effect could I have on a result with low probability or high probability?
Am I comfortable with a probabilistic test result?
If the test results indicate a high likelihood of trisomy 21, would I be willing to undergo amniocentesis knowing that this procedure carries some risk of miscarriage ?
What does life represent for me with a child with trisomy 21?Trisomy 21 Risk Normal Range
Would I be willing to have an abortion if the result of amniocentesis was positive for Trisomy 21?
It is not always easy to answer these questions, but thinking through them allows you to make an informed decision.

If you choose to take the prenatal screening test for trisomy 21, know that it is safe for the fetus.

What is trisomy 21?
Risk of carrying a fetus with trisomy 21
Screening tests
Result of prenatal screening test
What is trisomy 21?

Trisomy 21, also known as Down syndrome, is one of the most common chromosomal abnormalities. The child with trisomy 21 has an intellectual disability, which can range from mild to important. It is impossible, however, to predict the limits of one’s intellectual development, for they are not the same for all. The stimulation and support offered to children with trisomy 21 also help to push their limits.

Trisomy 21 Risk Normal Range

Although people with mental retardation are intellectually limited, they have the resources and potential to develop strong emotional relationships and thrive. Some Down Syndrome adults are even able to work and be relatively independent. Since no treatment exists for this chromosomal abnormality, most affected adults will require more or less support throughout their lives.Trisomy 21 Risk Normal Range

Health problems are often associated with trisomy 21, including visual disturbances (eg myopia, strabismus and cataract), auditory (deafness), cardiac and digestive disorders. More specifically, 40% to 50% of newborns will have a cardiac malformation and 5% to 10% of them will have gastrointestinal malformations. Early intervention and regular medical monitoring can, however, reduce some of these problems.

Risk of carrying a fetus with trisomy 21

All women can wear a fetus with trisomy 21 because this chromosomal abnormality is usually not hereditary. However, the risk of having a child with Down syndrome increases when the pregnant woman is older. For example, as shown in the table below, a 20-year-old woman is less likely to carry a child with trisomy 21 than a 40-year-old woman.

Risk of carrying a child with trisomy 21
(term pregnancy)
Age of the pregnant woman
.20 years—>     1 case in 1,500
.30 years — >   1 case out of 900
.35 years —->    1 case out of 385
.40 years —->    1 case out of 100

Screening tests

Blood samples

Available free in Quebec, the prenatal screening test for trisomy 21 requires 2 blood tests. The first takes place between the 10 th and 13 th week ( Q1 ), while the second is made between the 14 th and 16 th week ( Q2 ). Combining the risks associated with your age and the results of these 2 Trisomy 21 Risk Normal Rangesamples will determine if it is unlikely or very likely that you would give birth to a child with trisomy 21.

Trisomy 21 Risk Normal Range

To obtain a more accurate result, you must submit to 2 blood tests. However, it is possible to calculate your chances of having a baby with trisomy 21 if you only take one sample. On the other hand, the result you will obtain will be less reliable since, with a single sample, the rate of false positives increases significantly and the rate of detection of the anomaly decreases.

Ultrasonography: measurement of nuchal translucency

Between the 11 th and 13 th week of pregnancy, your doctor or midwife may suggest an ultrasound to measure nuchal translucency of the fetus, that is to say the space between the skin of his neck and spine. If this space is larger than normal, the risk of trisomy 21 is high because children with this abnormality have a thicker neck skin fold. The risk of other chromosomal abnormalities or cardiac malformations is also high. To increase the reliability of this test, measurement of nuchal translucency should be combined with blood test results.

Result of prenatal screening test

The results of the prenatal screening test are presented as probabilities. Thus, you will know if it is very unlikely that you will give birth to a child with trisomy 21.If your risk is low (less than 1 in 300 chance of giving birth to a baby with trisomy 21), you will have no other tests to pass. However, you could still have a baby with trisomy 21 because the probabilities are never zero. Due to the personal characteristics of each person, blood sampling and nuchal translucency measurement do not identify all fetuses with trisomy 21.Trisomy 21 Risk Normal Range
If your risk is high (1 chance in 300 or more to give birth to a baby with trisomy 21), this does not mean that your baby will certainly be diagnosed with trisomy 21. The professional who follows your pregnancy will propose an amniocentesis with chromosome study. This test makes it possible to know if the fetus has trisomy 21 or another chromosomal anomaly. The majority of women who undergo amniocentesis get a normal result and give birth to a baby who does not have trisomy 21.


Pregnancy Ultrasound

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