You can find out who the father is during pregnancy through a simple blood test as early as eight weeks. This non-invasive prenatal paternity test, known as NIPP, is 99.9% accurate and poses no risk to the pregnancy. Two older methods, CVS and amniocentesis, also work but involve needles entering the uterus and carry small risks of miscarriage.
Non-Invasive Prenatal Paternity Testing
Starting around four weeks of pregnancy, fragments of the baby’s DNA begin circulating in the mother’s bloodstream. By about eight weeks, enough of this DNA is present to be collected and analyzed. The test itself is straightforward: a healthcare provider draws blood from the mother’s arm and collects a cheek swab (or blood sample) from the potential father. A lab then compares the baby’s DNA fragments with the potential father’s DNA to confirm or rule out a match.
Between weeks 10 and 20, fetal DNA makes up roughly 10% to 15% of the total free-floating DNA in maternal blood. Labs generally need at least a 4% fetal fraction to produce a reliable result, which is why testing before eight weeks isn’t recommended. The accuracy rate is 99.9%, making it just as reliable as a paternity test done after birth.
Because NIPP requires only a blood draw, there is no risk of miscarriage or harm to the baby. This is the option most people choose today, and it has largely replaced the invasive methods that were once the only way to test paternity before delivery.
Invasive Options: CVS and Amniocentesis
Before NIPP existed, the only prenatal paternity tests required collecting tissue or fluid directly from the uterus. These procedures are still available, though they’re rarely chosen for paternity alone because of the associated risks.
Chorionic villus sampling (CVS) is typically performed between weeks 10 and 12. A provider uses a thin needle or catheter to collect a tiny sample of placental tissue, which contains the baby’s DNA. The miscarriage risk associated with CVS is approximately 0.5% to 1.0%, or roughly 1 in 100 to 1 in 200 procedures.
Amniocentesis is done later, usually between weeks 14 and 20. A needle is inserted through the abdomen to withdraw a small amount of amniotic fluid surrounding the baby. When performed by an experienced provider using ultrasound guidance, the miscarriage risk is lower than CVS, around 0.1% to 0.3%. Amniocentesis done before 15 weeks carries a higher risk of pregnancy loss than when done later in that window.
Both procedures provide highly accurate DNA for paternity comparison, but given that NIPP delivers the same accuracy without any physical risk, most providers will not recommend CVS or amniocentesis solely for paternity purposes.
What the Test Costs
Prenatal paternity testing ranges from about $400 to $2,000 depending on the method and lab. Non-invasive blood-based testing tends to fall on the higher end because isolating fetal DNA from maternal blood requires specialized technology. A common price point for NIPP using current methods is around $1,600. Insurance typically does not cover paternity testing since it’s considered elective rather than medically necessary.
Testing done after the baby is born is significantly cheaper, often under $500. If cost is a major concern and you’re not in a time-sensitive legal situation, waiting until after delivery is the most affordable route.
If You Need Results for Court
A paternity test you order on your own, sometimes called a “peace of mind” test, will give you an answer but won’t hold up in legal proceedings. Courts require what’s called chain of custody documentation, a detailed paper trail proving that the samples came from the right people and were never tampered with.
For a legally admissible test, several conditions must be met. Samples have to be collected at a certified facility by a trained professional, not at home. Every person being tested must show government-issued photo ID, and many labs also photograph participants. The samples are sealed, labeled, and tracked at every step from collection to analysis. The lab performing the test must be accredited by the American Association of Blood Banks (AABB), which sets strict standards for accuracy and handling.
If you think paternity results might eventually be needed for child support, custody, or any other legal matter, it’s worth paying for the legal version from the start. Running a second, court-admissible test later means paying twice.
When Each Option Is Available
- NIPP (blood test): From 8 weeks onward. No risk to pregnancy. Most widely recommended.
- CVS: Weeks 10 to 12. Small miscarriage risk (0.5% to 1.0%). Rarely used for paternity alone.
- Amniocentesis: Weeks 14 to 20. Lower miscarriage risk (0.1% to 0.3%). Also rarely used for paternity alone.
- Postnatal test: After birth. Cheapest option. Cheek swab from baby and potential father.
Situations That Can Complicate Results
If the potential fathers are closely related, such as brothers, standard paternity tests can sometimes produce less clear-cut results because relatives share a significant portion of their DNA. In these cases, testing both potential fathers rather than just one gives the lab enough information to distinguish between them. Let the testing company know about this ahead of time so they can adjust their analysis accordingly.
Pregnancies with twins or other multiples can also add complexity. If the babies have different fathers (which is rare but possible), the mixed fetal DNA in the mother’s blood may require additional testing or may need to wait until after birth for definitive answers. A testing provider can walk you through your specific situation before you commit to a method.