WITH a polycystic ovary syndrome diagnosis making her periods impossible to regulate, assurance from Google that she would have a hard time getting pregnant, and the "excitement of being young", added to an affinity for vodka mixed drinks, when she actually did get pregnant two years ago, 26-year-old banker Nicole B found it impossible to calculate which of the two men she was casually dating was her child's father.

"Rather than speculate, or wait to see what the baby looked like, or hurt two men for nine months, I took the route of testing while I was pregnant," the master's student said. "It was quite a simple process, a bit expensive yes, but I would advise women to do this, instead of pinning the wrong babies on men."

With the non-invasive prenatal paternity test (costing upwards of $200,000), you can get a DNA test before the baby is born, which can be performed after the seventh week of pregnancy. This involves taking a small sample of blood from the mother and a swab from the cheek of the possible father. The test does not pose any risk to the mother or baby.

"The test is extremely reliable and can be depended on to return a 99 per cent or higher probability of paternity if the man who is tested is considered to be the biological father, or a zero per cent probability of paternity if he is not the father," obstetrician/gynaecologist Dr Sharmaine Mitchell advised in the Observer.

She said the DNA paternity test, when done before delivery, can be a better choice than if done after delivery for some expectant mothers for several reasons.

"This lessens the stress associated with the uncertainty of the two fathers during the pregnancy. Constant stress can have negative effects on an unborn child. This includes low birth weight and premature delivery. Not knowing who the father of the child is can result in chronic stress, so getting the answer through a prenatal paternity test can help to take the load off your mind."

Knowing who the father is before birth can also help to create a better relationship between mother and father, as Nicole testified to, and also, in her case, helped have the right man be involved from the get-go.

"When two or more possible fathers are in the picture, a prenatal paternity test can help you find the answers you need to make decisions about personal ties. Waiting until after the baby is born can complicate the process significantly," said Dr Mitchell.

Prenatal paternity testing can also help to make pre-arrangements for child support and custody issues. When you do the paternity test while pregnant you can have the confidence that the right person is participating in the birth of the baby and the right name goes on the birth certificate.