To conduct the test, it is necessary to examine the biological material of the child, his mother and the alleged father. Similar studies are carried out in laboratories of specialized clinics, where the percentage coincidence of consecutive combinations of DNA of the alleged relatives is determined.
The coincidence in all the DNA fragments of a child and a man means, that a man with a probability of 99% accounts for the father of this baby. With two or more discrepancies, paternity is considered unconfirmed, and the man from the applicants is excluded.
Such a test can be carried out even at the stage of pregnancy, when the child is still in the womb (or a surrogate mother). Of course, it is better to carry out such a test after the birth of the baby, avoiding such an intervention, because it carries a serious threat of infection of the amniotic fluid or the fetus and, in addition, can provoke miscarriage or premature birth. However, in some emergency cases (when, for example, a woman doubts who the child was conceived from, or the alleged father believes that he is not involved in his appearance), paternity is established without fail. If, on examination, a man insists, and not a woman, then the test can be conducted, but only in a judicial order.
To date, only a DNA test is a scientifically grounded and provable method of establishing kinship. The results of other methods and tests during pregnancy, unfortunately, are still imperfect or do not guarantee their infallibility. So, for example, if a woman after the last month had several unprotected sex with different men, then the estimated paternity can be determined by the method of counting, that is, the most probable time of conception is the period of ovulation (mid cycle) - approximately 14-15 days after menstruation. In this case, most likely, the father of the child will be the man with whom there was sexual intercourse in this period of time. However, this method can not be reliable if:
- the woman did not follow her menstrual cycle for the past six months, marking the day of ovulation;
- if in the middle of ovulation (+/- 2 days) there were still more than 1 sexual partner, because in the wet alkaline environment of the uterus and fallopian tubes, sperm can maintain its fertility within 2-3 days, and then longer.
DNA tests to establish paternity during pregnancy
Modern medicine has two methods of conducting a DNA test during pregnancy - non-invasive and invasive, which differ in that the first is performed without intervention in the uterine cavity of a pregnant woman, and the second is carried out with the help of special equipment with penetration inside the uterus.
How is the DNA test for paternity carried out by a non-invasive method?
For more accurate results of this method of testing, it is used on terms 10-16 weeks of pregnancy, and it is the most safe for the future mother and her baby. Specialized clinics or laboratories engaged in DNA testing have high-precision equipment and reagents that allow you to determine paternity with high accuracy (up to 99, 9%) during pregnancy, and for this purpose it is sufficient to conduct an analysis of the venous blood of the alleged father of the child (10 ml) and mother (20 ml). Blood sampling can be performed in any medical institution as for routine blood testing, and then sent to a specialized laboratory. The mother of the blood takes more, since the fetal DNA is extracted from her in the form of fragments.
The high percentage probability of a test in his conclusion means that the prospective father and child among several thousand random individuals have the same genetic markers.
However, a non-invasive method of testing will be unreliable if one of the parents has received a bone marrow transplant or blood transfusion less than six months before testing.
How is the paternity test done during pregnancy by an invasive method?
An invasive method of testing DNA involves the removal of tissue samples, biological fluids, blood by penetrating the natural external barriers of the mother and fetus. The procedure is carried out only in the conditions of a specialized medical institution.
To conduct a DNA test by an invasive method, in addition to the perinatal biological material of the child, DNA samples of the mother and the alleged father are needed. For this, you can use:
- scrapings from the cheek,
- biomaterial from the toothbrush,
- hair with hair bulbs,
- dry blood,
- sperm, etc., from which DNA can be extracted.
In parallel with the research on paternity, a check can be made for genetic diseases (for example, Down's syndrome) or, conversely, under the pretext of testing hereditary diseases, it is also possible to establish paternity. The research can be conducted anonymously.
Parents of the child should be warned about the possible risks associated with the methods of taking the perinatal material during the invasive method.
After sampling the necessary biological material for research and isolating the child's DNA from it using microarrays with a large number of genetic markers (hundreds of thousands of variants) and special computer programs, the samples are compared and the data processed. The test takes 5-7 days.
Carrying out a DNA test during pregnancy is not an easy task, much more difficult than conducting a similar test of an already born child. And only a very experienced specialist can cope with the fetal collection procedure (otherwise there is a risk of losing the baby).
However, not to trust the reliability and correctness of the medical report (the accuracy of the examination is 99-100%), the test has no basis, since neither the illness of the mother nor any other processes occurring in her body in this time, do not affect its result. However, in the case of a risk of developing complications or the threat of miscarriage, the procedure for establishing paternity is postponed until the baby is born.
The results of DNA testing can be notarized and used as an official proof of paternity in litigation.