According to statistics, every 600-800 children are born with Down syndrome. Risks increase with late pregnancy (after 35 years). But young women are not immune from this. Although, for example, a 20-year-old girl without genetic diseases in her and her husband's families has a 1: 2000 risk of developing this pathology.
That after the birth of the child did not have to regret to wonder, doctors offer future mothers to undergo screening-diagnostics to determine possible pathologies in the development of the fetus, including Down's syndrome.
Screening tests for pregnancy
There are several diagnostic methods that allow you to suspect the development of pathology in the fetus even in the intrauterine period. Today women are offered to undergo such research if they wish. The most popular is non-invasive antenatal (i.e., antenatal) diagnosis. This is primarily a blood test for hCG (human chorionic gonadotropin) and AFP (alfa-fetoprotein), as well as ultrasound of the fetus.
We have already written a lot about HCG on our website - we suggest reading it. We only note that the analysis for hCG is given at a period of 10-13 weeks.
Alfafetoprotein is a special protein, which produces the liver of the fetus. It is released into the amniotic fluid, from where it enters the blood of a pregnant woman. And according to the level of AFP in the venous blood of a future mother, you can draw certain conclusions. Thus, an underestimated level may be evidence of the development of Down's syndrome in a fetus, and an overestimated one - pathology of the neural tube. The level of AFP is constantly increasing with the increase in the term. However, the difference between normal, overstated and underreported indicators is most pronounced in the period from 16 to 18 weeks. It is at this time most appropriate to do this analysis.
Regarding ultrasound, for the purpose of screening diagnosis during pregnancy, it is carried out from the 10th to the 13th week. A good specialist already at this time can notice the formation of cervical folds in the fetus, because in the back of the neck with Down syndrome, subcutaneous fluid accumulates, which allows one to judge the developing pathology in the early stages of pregnancy. Down syndrome can also indicate the absence of nasal bone in the fetus (70% of cases of development of this pathology, it is not visible).
Despite the fact that early diagnosis of blemish is very important for expectant mothers, such screening tests do not give absolute guarantees of accuracy. With the same probability, studies can show both false-positive and false-negative results. And then the question of a chorionic villus biopsy may arise. A probe with a mirror is inserted through the vagina, a sample for analysis is rarely taken by inserting a needle through the abdominal cavity into the uterus. However, the risk of miscarriage as a result of this procedure is significantly increased and is 1: 360.
Another more accurate method of diagnosing is the amniocentesis in comparison with ultrasound and blood analysis, but it does not give absolute guarantees of reliability.
Amniocentesis involves the study of amniotic fluid. For this, a pregnant woman is pierced with a stomach to take an amniotic fluid for a biopsy.
Do a screening test or not?
However, not everything is so simple. Non-invasive diagnostics allows only to suggest the development of Down's syndrome in a fetus. And note that for this ultrasound should be carried out by a highly qualified specialist. Concerning the analysis of blood on the AFP, it also can not be perceived as a diagnosis. The results depend on many factors, since the level of alfa-fetoprotein may vary, for example, under the influence of smoking. Of great importance in correct reading of results has also a very precise definition of the gestational age. In addition, there are no clearly defined indicators of the level of AFP in the blood, which could clearly indicate the presence of pathology. Therefore, we are talking only about suspicions or assumptions, about the possible probability of a defect.
If the results of screening studies reveal a high risk of developing pathology, a woman is offered to undergo amniocentesis. Only after this, the final diagnosis can be made, and the one, as we have already said, is not absolutely reliable. But the amniocentesis can be done no earlier than the 18th week, because before that amniotic fluid is not enough. Please note that the results will come in about two to three weeks. And this is a term of 5 months, when a person lives inside of you. And with the confirmation of fears before the woman there will be a serious choice: to kill him or not? Important is the fact that from a physiological point of view, abortion (and in fact, artificially induced births) at this time is very dangerous. Yes, and in the psychological, perhaps, it will not be better.
Why do we tell you all about this? There are statistics that in the overwhelming majority of cases of development of chromosomal abnormalities of the fetus, such a pregnancy naturally ends in miscarriage early in life (mainly up to 8 weeks). There are other statistics that indicate that in the vast majority of cases, the invasion of the intrauterine world by piercing the abdomen and taking the amniotic fluid has its own consequences. Among them: spontaneous miscarriage, infection of the fetus, damage to the bladder, an exacerbation of Rh-conflict, the absence of any results of amniocentesis (which occurs in 5% of all cases) and other complications.
And there are statistics that in the vast majority of cases this happens with quite healthy children, who decided to check. If a woman refuses an amniocentesis, she often gives birth to a healthy baby. But if before she passed a screening test that suspected something wrong, then until the child's birth, obsessive fear still does not leave her.
We do not encourage you to refuse screening. You just need to know that this anomaly does not lend itself to treatment. And the final diagnosis to you can put only by the end of the fifth month of pregnancy.
And we will remind once again that in most cases, women, who were at risk of noninvasive diagnosis, but refused further research, healthy babies were born. What we really really want!