A prenatal paternity test determines the biological relationship between a potential father and an unborn child during pregnancy, starting as early as the 9th week. There are two main types: non-invasive, using maternal blood and father's cheek swab, and invasive, involving amniotic fluid or placental tissue. Non-invasive testing is accurate but costly, while invasive testing carries a slight miscarriage risk. This testing can establish paternity for personal, legal, or emotional reasons, and consulting a healthcare provider or genetic counselor is advised to weigh risks and benefits.