Sometimes confusing life circumstances develop in such a way that even before the birth of a child, it becomes necessary to conduct paternity tests in order to establish who the woman is pregnant with. Do not rush to throw a stone at a man who wants to make sure that he is the father of the future baby. It's just that fatherhood is no less responsible than motherhood, and situations, as already mentioned, can be very confusing. A prenatal (prenatal) DNA test can help establish the truth.
What it is?
Earlier, geneticists could not establish paternity before the birth of a child. A little later, methods appeared, but this was associated with an unjustified risk in this case - in order to obtain materials (blood, amniotic fluid, baby epithelium particles), according to which a comparative analysis of the DNA of a potential dad and a baby, it was required to conduct prenatal invasive diagnostics. In other words, it was necessary to make a puncture of the fetal bladder and take materials for analysis. This increases the likelihood of intrauterine infection, termination of pregnancy, and establishing paternity is not a compelling reason for invasive diagnosis.
The modern test (NIPT) is not invasive. That is, it is not associated with any risks for the expectant mother and baby, while its accuracy is no less high. Is this research credible? Certainly. And that's why.
DNA is the main source of all hereditary information. The child has his own DNA, but it consists of paternal and maternal chromosomes (23 from each parent). The process of genome formation occurs in the first 12 hours after the fertilization of an egg with a sperm.
Therefore, the child's DNA obtained from the material for research (about it - below) necessarily contains the paternal and maternal chromosomes, which make it possible to identify the relationship as accurately as possible.
Basically, there are two ways to make tests:
- apply invasive diagnostics;
- do an NIPT (non-invasive test).
In the first case, DNA is isolated from fetal biomaterials: blood particles, epithelium, water. In the second case, there is enough maternal blood from a vein - for a period of more than 9 weeks of pregnancy, according to obstetric standards, the baby's erythrocytes partially penetrate into the mother's blood, which allows them to be isolated and DNA tested.
Both tests will be informative, but each comes with its own medical and legal challenges.
Who is the initiator?
This question is very important.
The woman's consent is required to administer the test using either method. Without her voluntary informed consent, in which she will sign, analyzes in any way cannot be carried out for compelling legal reasons.
For a prenatal invasive test initiated by a woman, it is important to contact a gynecologist. A woman's doubts about who the true dad is, of course, are not grounds for a traumatic invasion of the uterus. And therefore, the expectant mother will first be told about how horrific the consequences for the child can be - death, termination of pregnancy, intrauterine infection, trauma to the baby with long sharp needles that puncture the wall of the uterus to obtain biomaterial. If the lady continues to insist after that, she will undergo invasive diagnostics.
A non-invasive DNA test involves only taking blood from a vein and is carried out with the written consent of the pregnant woman for such an examination (in fact, a regular blood test). The examination is paid, it is not carried out under the compulsory medical insurance policy, it is not done in every clinic, but in specialized medical and genetic centers.
If the future dad insists on the paternity test (which happens a little more often), then his possibilities are generally limited. Anyway he needs to get consent to examine the woman... Without him, the man in the test will be categorically denied. We'll have to wait until the baby is born to insist on a genetic analysis of the relationship (by a court decision or by the free consent of the parties).
If a man and a woman are officially married, then the establishment of paternity for a man during the wife's pregnancy and after childbirth should be discussed in court.
Where and how are tests done?
Invasive antenatal diagnostics are carried out by medical genetic centers, family planning centers, as well as perinatal centers with genetic laboratories. NIPT can also be carried out by private clinics licensed to conduct genetic examination.
A non-invasive test does not require much time and effort - you need to come to the center on the appointed day, on an empty stomach, and donate blood from a vein. It is important to remember that at the time of the analysis, the gestational age must exceed 9 obstetric weeks (approximately 7 weeks from conception or 5 weeks from the start of the missed period).
With an invasive test, a woman must arrive at a medical facility in advance (several hours or a day). The procedure is unpleasant - under the control of ultrasound, a long hollow game is inserted into the uterus through the anterior abdominal wall or the fornix of the vagina, with which material is taken for research. For this prenatal test, it is better to choose a later pregnancy period - after 12 weeks. Up to 12 weeks, the accuracy of the result can be questionable.
For research, they can take chorionic villi, fragments of the placenta or placental blood, blood from the umbilical cord (cordocentesis) or amniotic fluid in particles of the baby's epithelium (amniocentesis).
In both cases, doctors will also need a blood sample from the father to isolate his DNA. For research, venous blood is usually taken.
Important! In both cases, the analysis accuracy exceeds 97-99%.
In the case of invasive diagnostics, it can take about 3 weeks to get the result. NIPT results can be obtained a little earlier - in 10-14 days. Terms are conditional, in each laboratory they can be different, taking into account the workload, sequence and capacity of the equipment. Also remember that the cost of invasive diagnostics is about three times lower than non-invasive ones (in the central regions of Russia, the cost of NIPT in 2019 on average ranges from 45 to 90 thousand rubles).
In what cases is the analysis not performed?
You can establish paternity during pregnancy only if the woman is pregnant with one fetus. With multiple pregnancies, the likelihood of a DNA test error before the baby is born is much higher. In addition, medicine knows cases when twins had different biological fathers in the mother's womb.
A paternity test is also not carried out if a surrogate mother is carrying the baby. Firstly, paternity in this case is quite accurately known (fertilization took place through IVF), but if the man has doubts and he suspects that the doctors of the reproductive medicine clinic could have made a mistake or changed the material, then the test will have to be done after the child is born. Secondly, a surrogate mother cannot provide a mother's blood sample - she and the baby she is carrying have nothing in common in DNA.
A non-invasive DNA test is not done after a recent bone marrow transplant, or after a woman has recently transfused donated blood. The analysis will not be carried out if the woman disagrees with this formulation of the question.
Common questions
Individual situations can be very different, and quite unusual questions often arise. For example, is it necessary to undergo tests for both men, if the possible fathers are not strangers to each other, but blood relatives, for example, brothers. Yes, in this case, both brothers or other relatives must take tests. - this is important to refine the results. Otherwise, the analysis can show the paternity of each of them.
The question of which method is preferred is difficult to answer unequivocally. An invasive test carries possible risks to the health of the woman and the fetus. And non-invasive is quite expensive. From a safety point of view, it is better to choose NIPT.
