A prenatal paternity test can identify whether a man is a baby's father before the baby is born (during pregnancy).
Prenatal paternity testing is a sensitive subject because of the ethical and moral issues involved, including the risks of an invasive test (see below). Many doctors are unwilling to carry out a prenatal paternity test, especially if confirming the baby's father's identity is the only reason for the test.
For example, if a prenatal paternity test is carried out and the test result is unexpected, the woman may not want to continue with the pregnancy. An unwanted paternity test result is, however, unlikely to be considered adequate grounds for terminating a pregnancy abortion.
If you're pregnant and thinking about a prenatal paternity test, talk to your GP or midwife. They can help you consider the issues involved, as well as advise you about the risks for you and your unborn baby. They can also arrange counselling.
Paternity tests can also be carried out after a baby is born. If you're considering any paternity test, it's important to consider the issues involved carefully. Prenatal and other paternity tests are not available on the NHS.
DNA and prenatal paternity tests
A baby inherits DNA from both its parents. Prenatal paternity tests can identify if a man is the father of a baby by looking at samples containing:
- the man's DNA
- the pregnant woman's DNA, and
- the unborn baby's DNA
DNA from the man and the pregnant woman
The man and the pregnant woman each provide a sample containing their DNA so it can be analysed. For example, a sample of cheek cells from inside the mouth or a blood sample.
If a paternity test is required for legal reasons, the samples must be taken under strict conditions, as required by the court.
DNA from the unborn baby
So that the unborn baby's DNA can be analysed, the pregnant woman will also need to provide a sample of:
- fluid from the womb (amniotic fluid) containing cells from the baby
- tissue from the placenta
A sample of fluid from the womb is collected by inserting a needle through the abdomen. This procedure is called amniocentesis.
A sample of tissue from the placenta is collected by passing a needle through the wall of the abdomen, or passing a small tube through the vagina and the neck of the womb (cervix). This procedure is called chorionic villus sampling (CVS).
Amniocentesis and CVS have a small risk of miscarriage.
Consent for prenatal paternity tests
As with any medical treatment or test, the woman must consent to the samples being taken and tested.
Under the Human Tissue Act 2004, prenatal paternity tests done in the UK must also have the consent of the man or men involved.