Amniocentesis: This is an invasive prenatal paternity test that is done in the pregnancy’s 2nd trimester (between the 14th and 20th pregnancy week). When carrying out amniocentesis, the practitioner inserts a thin needle through the abdomen and into the uterus with the guidance of ultrasound. Some amount of amniotic fluid is drawn using the needle for testing. There is a slight but significant risk of injuring the child or causing a miscarriage. The mother may also experience cramping, bleeding in the vagina and amniotic fluid leakage. 
Chorionic Villus Sampling or CVS: In this invasive prenatal test, the doctor inserts a thin tube or needle through the vagina to the cervix to draw some chorionic villi tissue which is attached to the uterine walls. The fetus and the chorionic villi have identical genetic component as they’re from the same fertilized egg. 
Non-invasive prenatal paternity test is generally recommended, and for obvious reasons. It helps sidestep unnecessary side effects and avoid the potential of losing your baby that is present in other types of prenatal paternity testing. 
Legality of prenatal paternity testing
The results of a non-invasive prenatal paternity test can be accepted in a court of law whenever necessary. The results of private test and a test necessitated by litigation are the same, but legal testing needs the laid-out legal procedures to be followed strictly. For example, the mother and the suspected father ought to be properly identified, there’s need for an eye witness for the drawing of the respective fluids and some legally binding paperwork. The high accuracy of prenatal paternity testing makes it enough legal proof of a paternal relationship.