All about prenatal DNA testing

With prenatal DNA paternity testing it is possible to identify whether a man is a baby’s father before the baby is born. In other words, the DNA test is performed whilst the mother is still pregnant. This is a non-invasive test, which can be performed as early as 5 weeks after conception (or 7 weeks after the last period).

The testing process works on the same principle as standard DNA paternity tests. By examining the baby’s DNA together with the parents’ DNA, it is possible to identify which half of the DNA is inherited from the mother and which half is from the father. If the tested man is indeed the biological father of the baby, both will share DNA. When the tested man is not the biological father there will be differences in the DNA of the man and the baby. Confidentiality is maintained throughout the process.

What samples are required?

Prenatal paternity tests can identify if a man is the father of a baby by looking at three samples:

  • the man’s DNA
  • the pregnant woman’s DNA, and
  • the unborn baby’s DNA

Prenatal DNA testing works by analysing the baby’s DNA that is found within the mother’s bloodstream. Therefore, to gain a sample of the baby’s DNA a blood sample is needed from the pregnant mother. Mouth swabs are also needed to collect DNA samples from the alleged father.

There is no risk to the unborn child when taking this prenatal DNA test. A blood sample is only needed from the mother: no needles need to be inserted into the womb.

How are the samples collected?

Consent is needed from both the man and the pregnant woman for the prenatal test to be performed.

The mother’s blood sample collection can be performed by a nurse or phlebotomist at a local medical practice. Alternatively, AlphaBiolabs can arrange for one of its highly-trained sample collectors to take the sample from any convenient location (this could be your home or place of work, for example).

Blood samples are time sensitive and need to be returned to AlphaBiolabs’ testing laboratory as soon as possible after being collected. This is to avoid haemolysis (the breakdown of red cells), which can have an effect on the laboratory results. For this reason, the use of a trained sample collector is highly advised.

The alleged father’s sample involves just a mouth swab to collect DNA as in a standard DNA paternity test. The mouth swab simply needs to rubbed firmly on the inside of both cheeks for at least 20 seconds to collect cheek (buccal) cells. The man’s sample does not need to be collected at the same location as the mother’s blood sample; a sample collector can visit any convenient location. However, the samples should be collected around the same time to avoid any delays.

Another option for sample collection is to use one of AlphaBiolabs’ nationwide Walk in Centres. Here both blood and mouth swab samples can be collected at the same time, which could save money on collection fees.

How are the DNA tests performed?

DNA is extracted from the alleged father’s and mother’s samples back at AlphaBiolabs’ laboratory. In-house geneticists then examine up to 35 short tandem repeat (STR) markers in these DNA profiles. The baby will have two copies of each STR marker, known as alleles: one is inherited from the father and the other from the mother. These alleles at each STR marker are compared between the donors. There needs to be a match with all STR markers tested for an inclusion of paternity.

State-of-the-art equipment is used to separate the baby’s DNA from the mother’s DNA in the blood sample using single nucleotide polymorphism (SNP) microarray technology. A technologically advanced technique known as Massively Parallel Sequencing (MPS) is then used to generate data from the samples that need to be analysed and interpreted.

Why are we the fastest prenatal DNA tester in the industry?

It takes days to prepare the DNA samples before they are run on our advanced DNA instrumentation, which takes a further 24 hours. A lot of data are generated, which then needs to be analysed by members of our expert team of DNA scientists. If samples fail to meet the quality criteria, and need to be reprocessed, this lengthy process needs to be repeated. This is why prenatal DNA testing is a much longer process than standard DNA relationship testing. Turnaround times are usually a few weeks, but results from AlphaBiolabs can be expected within 4–7 days depending on what level of test you choose.

Further information on Prenatal DNA testing can be found in our FAQs below.


How do I order a prenatal DNA test?

You can order your test here and one of our Customer Services team will be in touch to arrange your sample collections.

Alternatively, you can email or call Customer Services on 0333 600 1300. We can talk you through the process and outline the next steps.

Is a sample needed from the alleged father?

Yes. We need samples from both the mother and alleged father.

Can the samples be collected at different locations?

The samples do not need to be collected at the same location. However, the samples should be collected around the same time to avoid any delays and the risk of the blood samples haemolysing.

What samples are required?

Two mouth swabs are needed from the alleged father, and two blood samples from the mother.

What are the options for sample collection?

The blood samples are time sensitive and need to be collected by a trained nurse, a phlebotomist, or an AlphaBiolabs fully trained sample collector. The mouth swabs also ideally need to be collected by an AlphaBiolabs sample collector. Both of these samples can be collected at the same time, or separately, at one of our nationwide Walk in Centres. Alternatively, you can choose to organise your own sample collections.

What if a recollection is required?

If the blood or mouth swabs have insufficient DNA then a recollection will be needed. An appointment can be arranged to recollect any samples or a new testing kit can be sent out. Please note that you are responsible for the cost of all blood collections.

How early can the test be performed?

This non-invasive prenatal test can be carried out as early as 5 weeks after conception (or 7 weeks after the last period). You can use our pregnancy calculator to work out how many weeks pregnant you are.

Can the test harm the baby?

There is no risk to the unborn child when taking this test. Non-invasive prenatal testing uses a simple blood sample from the mother and therefore does not require a needle to be inserted into the womb.

What are the risks?

There is no risk to the baby or the mother.

Why should invasive procedures be avoided?

To gain a sample of an unborn baby’s DNA invasively, a sample of amniotic fluid from the womb can be collected by inserting a needle through the abdomen: this procedure is called amniocentesis. This amniotic fluid contains cells from the baby that can be analysed. Alternatively, a sample of tissue from the placenta can be collected by passing a needle through the wall of the abdomen, or by passing a small tube (catheter) through the vagina and the neck of the womb (cervix): this procedure is called chorionic villus sampling (CVS). Both of these invasive methods incur a slight risk to the unborn child, with a 1% chance of miscarriage with CVS and a 0.5% chance of miscarriage for an amniocentesis.

What are the chances of getting a conclusive result?

In the majority of cases, we provide at least 99% probability of paternity where the father is confirmed as being the biological father. However, a conclusive result cannot always be guaranteed because of the scientific limitations of non-invasive prenatal paternity testing.

In the event of there being insufficient foetal DNA in the mother’s blood, we offer up to two additional tests free of charge (collections need to be at least 2 weeks apart) with newly collected samples. However, there is still the cost of the blood sample recollection which we cannot refund.

In approximately 3–5% of cases, foetal DNA never reaches a sufficient level for successful testing. This is considered an inconclusive result and we will therefore refund the cost of your DNA prenatal paternity test.

What is the turnaround time?

Results can be made available in 4–7 working days depending on the level of service you choose.

Can I get my results faster?

Our express service can get your results back to you in just 4 working days (for an additional £200).

How much does the prenatal DNA test cost?

Results can be made available in 7 working days for £875. An express service to get your results back in just 4 working days is also available for an additional £200.

A 6-month interest-free credit payment option is available.

Order your test online by clicking here or call AlphaBiolabs on 0333 600 1300