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High risk of Down syndrome?
Down syndrome is not a disease, it is a pathology that cannot be prevented and cured. A fetus with Down syndrome has a third extra chromosome in the 21st pair of chromosomes, as a result, their number is not 46, but 47. Down syndrome is observed in one in 600-1000 newborns from women over the age of 35. The reason why this happens , has not been fully elucidated. The English physician John Langdon Down first described the syndrome in 1866, and in 1959 the French professor Lejeune proved that it was due to genetic changes.
It is known that children receive half of the chromosomes from the mother, and half from the father. Since there is not a single effective method of treating Down syndrome, the disease is considered incurable, you can take measures and, if you want to give birth to a healthy child, contact a medical genetic consultation, where, based on the chromosomal analysis of the parents, it will be determined whether the child will be born healthy or with Down syndrome.
Recently, such children are born more often, they associate this with late marriage, with pregnancy planning at the age of 40. It is also believed that if a grandmother gave birth to her daughter after 35, then grandchildren may be born with Down syndrome. Although prenatal diagnosis is a complex process of examination, it is very necessary in order to be able to terminate the pregnancy.
What is Down Syndrome. It can usually be accompanied by a delay in motor development. Such children have congenital heart defects, pathology of the development of the organs of the gastrointestinal tract. 8% of people with Down syndrome have leukemia. Drug treatment can stimulate mental activity, normalize hormonal imbalance. With the help of physiotherapy, massage, therapeutic exercises, you can help the child acquire the skills necessary for self-care. Down syndrome is associated with a genetic disorder, but this does not always lead to a violation of the physical and mental development of the child. Such children, and in the future adults, can participate in all spheres of life, some of them become actors, athletes and can be involved in public affairs. How a person with this diagnosis will develop depends largely on the environment in which he grows up. Good conditions, love and care contribute to the full development.
Down syndrome risk table, by age
The likelihood of Down syndrome depends on the age of the mother, but it can be detected by a genetic test in the early stages of pregnancy, and in some cases by ultrasound. The likelihood of a child having Down syndrome at birth is lower than at earlier stages of pregnancy, because. some fetuses with Down syndrome do not survive.
What risk is considered low and what is considered high?
In Israel, the risk of Down syndrome is considered high if it is higher than 1:380 (0.26%). Anyone in this risk group should have their amniotic fluid tested. This risk equates to that of women who become pregnant at age 35 or older.
Risk lower than 1:380 is considered low.
But keep in mind that these borders can be floating! So, for example, in England, a risk above 1:200 (0.5%) is considered a high risk. This is due to the fact that some women consider the risk of 1 in 1000 to be high, and others 1 to 100 to be low, since at such a risk they have a 99% chance of having a healthy child.
Risk factors for Down syndrome, Edwards, Patau
The main risk factors are age (especially significant for Down syndrome), as well as exposure to radiation, some heavy metals. It should be borne in mind that even without risk factors, the fetus may have a pathology.
As can be seen from the graph, the dependence of the risk value on age is most significant for Down syndrome, and less significant for the other two trisomies:
Down Syndrome Risk Screening
To date, all pregnant women, in addition to relying on tests, are recommended to undergo a screening test to identify the risk of Down syndrome for childbirth and congenital malformations of the fetus. The most productive examination is at week 11 + 1 day or at week 13 + 6 days with the coccyx-parietal size of the embryo from 45 mm to 84 mm. A pregnant woman can be examined, and use a specific ultrasound for this.
A more accurate diagnosis is made with the help of a biopsy of the chorionic villi and the study of amniotic fluid, which is taken with a special needle directly from the fetal bladder. But every woman should know that such methods are associated with the risk of pregnancy complications such as miscarriage, infection of the fetus, development of hearing loss in the child, and much more.
Full combined screening of the I-II trimester of pregnancy allows to detect congenital malformations in the fetus. What does this test include? First, you need an ultrasound at 10-13 weeks of pregnancy. The risk is calculated by determining the presence of the nasal bone, by the width of the cervical fold of the fetus, where subcutaneous fluid accumulates in the first trimester of pregnancy.
In the second, a blood test is taken for chorionic gonadotropin at 10-13 weeks and for Alpha-fetoprotein at 16-18 weeks. Combined screening data are processed using a special computer program. Scientists have proposed a new screening technique – combining the evaluation of the results obtained in the course of research in the first and second trimesters. This allows for a unified assessment of the risk of Down syndrome during pregnancy.
For the first trimester, the results of determining PAPP-A and measuring the thickness of the collar space are used, and for the second trimester, combinations of AFP, unconjugated estriol, hCG and inhibin-A are used. The use of an integral assessment for screening examination allows, after invasive interventions, to reduce the frequency of abortion for fetuses with a normal karyotype based on the results of cytogenetic diagnostics.
Integral and biochemical testing for screening for Down syndrome allows additional detection of more cases of chromosomal abnormalities. This helps prevent unwanted abortions resulting from amniocentesis or chorionic villus sampling.