There was a time when running a DNA test on an unborn baby was risky and invasive, and the procedure was difficult for most people to access. Without and urgent medical reason, a doctor would be unable to justify the inherent risks to the baby. If the mother simply had doubts about the paternity of the father, that would not be adequate justification.
Up until very recently, a prenatal test involved passing a large needle through the abdomen and into the womb. The doctor would then collect a sample of amniotic fluid (o process known as amniocentesis), or alternatively a small piece of the placenta. That sample would then be analysed in a laboratory.
It's an unpleasant and invasive process - not to mention risky, as the doctor doing the test is essentially going in 'blind'. The NHS website advises that "amniocentesis and CVS have a small risk of miscarriage".
So what's the alternative?
If a pregnant woman is unwilling or unable to access a prenatal DNA test, the only other option is wait until the baby is born. Once the baby is out, you can run a 'traditional' DNA test which just requires a quick mouth swab. That however is about to change thanks to a modern technique involving cell-free fetal DNA.
Non-invasive testing
Scientists have recently discovered the presence of cell-free fetal DNA (ccfDNA) in the bloodstream of expectant mothers. Or to put it more simply, very small traces of the baby's DNA can be found in the mother's blood. ccfDNA is detectable from around 5 weeks after conception. Scientists are now able to take a blood sample and identify & extract the DNA of the unborn baby.
What does this mean for pregnant women?
It means no more moral or ethical dilemmas - a prenatal DNA test can be performed using a simple, routine blood sample, usually taken from the arm. It's less painful, less invasive and more dignified than the old style of prenatal testing. Most importantly, there is zero risk of causing a miscarriage.
New possibilities for genetic testing
Prenatal paternity testing is now a realistic possibility for thousands of women who want answers and can't wait until after the delivery. That said, there is a catch - as it's a non-essential treatment, anyone who wants a prenatal paternity test will have to stump up the cash themselves, and is isn't cheap. Commercial testing labs in the UK can charge anywhere from £350 to over £1,200 to carry out a prenatal paternity test. For comparison, a normal paternity test involving one child and one suspected father starts from around £99.
Other prenatal tests that are now safe & non-invasive include early gender testing and early testing for genetic diseases.
Where to get advice
Prenatal testing is certainly safer than it used to be, but anyone considering any kind of DNA test needs to weigh up the emotional consequence and the potential effects on their family & relationships. You can find impartial advice & support at https://www.citizensadvice.org.uk/family/