Amniocentesis is a medical investigation used for diagnostic screening or as a means of sample collection for a prenatal paternity test. The test can be performed between the 15-20th week of pregnancy (slightly after CVS, chorionic villus sampling) and involves the insertion of a needle through the abdomen in order to withdraw a sample of amniotic fluid. Amniotic fluid is the fluid which surrounds the unborn baby and is rich in fetal DNA. Amniotic fluid is an amber colored liquid. The issue with the procedure is that it can lead or miscarriage or to the leakage of amniotic fluid. If the level of amniotic fluid fall to low, this can be very dangerous for the baby. Because of these dangers, non invasive paternity tests are today available that do not require going anywhere near the uterus or baby as happens in amniocentesis.
It is important to note that non invasive tests only require blood samples. A blood sample is not collected from inside the womb but from the arm. There is no possibility of contact between the needle and the baby. Unlike amniocentesis or chorionic villus sampling, non invasive fetal maternal blood sampling is thus, a 0% risk test. Whilst for example, you would need to wait well into your second or third trimester to have amniotic fluid withdrawn for a a paternity test, a non invasive test is possible at around just 9 weeks. Find out more by reading an article comparing invasive and non invasive sampling methods.