Friday, June 25, 2010

Overview of the Prenatal Paternity Test

People who have questions or concerns about paternity and want to determine whether or not a certain man is the father of an unborn child may wish to have a prenatal paternity test conducted. Much like paternity tests that are done postnatal, or after the baby is born, the DNA from the mother, the fetus, and the alleged father are compared with one another to see if paternity is a possibility.

DNA and Establishing Paternity

The structure of deoxyribonucleic acid, or DNA, was discovered in 1953 and since that time, modern science has developed a number of intricate techniques that have allowed us to identify its complex make-up, and also to ascertain whether or not one person is related to another.

DNA is a molecule present within every cell of every living creature and under a powerful microscope, resembles a twisted ladder, which is why DNA is often referred to as the "double helix." This "ladder" is comprised of four base molecules, adenine, thymine, guanine, and cytosine that connect the "rungs," which are actually hydrogen bonds. The manner in which all of these molecules are arranges or structured is what is known as a DNA sequence, which are responsible for physical traits and characteristics as well as many other aspects related to heredity.

As cells divide and replicate, markers from both parent's DNA are equally present for a total of 46 chromosomes per cell. Through paternity testing, DNA is extracted through a process involving several distinct steps and then compared with other samples to determine if a match is present.

The Two Types of Prenatal Paternity Tests

Two different methods are used to collect DNA samples from an unborn child, both are considered to be invasive procedures and therefore present a certain amount of risk that should be discussed at length with the mother's obstetrician gynecologist (OB-GYN).

Chorionic Villi Sampling: Chorionic villi sampling, or CVS, is currently the earliest type of prenatal paternity testing that can be done on a fetus. CVS is done during the 10th through 13th weeks of pregnancy and collects cells from the placenta, which is the life-giving membrane that surrounds the tiny fetus. A doctor, usually the mother's obstetrician-gynecologist (OB-GYN), uses an ultrasound machine to guide either a hollow needle into the abdomen, or alternately, inserts a catheter into the vagina to collect the cells needed for testing.

Amniocentesis: Done during the 14th through 24th weeks of pregnancy, amniocentesis prenatal paternity testing collects loose cells from the fetus present within the amniotic fluid. Done by an OB-GYN, a long thin needle that is also guided by an ultrasound is inserted into the abdomen and into the amniotic sac to extract the fluid. The cells are retrieved and then processed in the same manner as other cells to ascertain DNA markers that would establish or rule out paternity.

Medical Risks Associated with Prenatal Paternity Testing

Because the two methods of prenatal paternity testing are invasive procedures, there is a certain amount of medical risk associated with both. With amniocentesis, there's the potential for injury to both mother or fetus from the needle, as well as the risk of puncturing the placenta, which in most cases, heals on its on without any harm to the baby.

Because a foreign object is being introduced into the amniotic sac, there's always the potential for infection, although this is a rare occurrence. Also, birth defects such as clubfoot is a concern with amniocentesis, particularly if the procedure is done prior to the 15th week of pregnancy. Always discuss any concerns or questions with your own doctor about prenatal paternity testing.

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